Rare earth clarifying agent and method for use in primary treatment of wastewater

ABSTRACT

Chloride salts of certain rare earth elements have beneficial effects as clarifying agents in the primary treatment of wastewater. Disclosed herein are methods for treating wastewater comprising dosing wastewater, as part of a primary treatment system, with a clarifying agent of chloride salts of rare earth elements, either individually or mixtures. The rare earth clarifying agents are added or dosed at any point upstream of the primary treatment operation, within the primary treatment operation, or both upstream of and within the primary treatment operation. Also disclosed herein are clarifying agents for use in the primary treatment of wastewater comprising an aqueous solution of chloride salts of the rare earth elements.

This application claims priority to U.S. Provisional Application Nos.62/580,246 filed Nov. 1, 2017, and 62/589,322 filed Nov. 21, 2017, bothof which are entitled “RARE EARTH CLARIFYING AGENT AND METHOD FOR USE INPRIMARY TREATMENT OF WASTEWATER” and are herein incorporated byreference in their entireties.

INTRODUCTION

Wastewater is a broad term that includes both human-generated wastewater(e.g., sewage) and industrial waste streams of water combined withvarious contaminants from the industrial process. Wastewater typicallymust be treated to remove at least some of the contaminants before itcan be discharged into the environment or reused.

Wastewater treatment commonly involves two stages, called primary andsecondary treatment. Primary treatment consists of temporarily holdingthe wastewater in a holding tank or basin where heavy solids can settleto the bottom while oil, grease and lighter solids float to the surface.The settled materials are removed as a sludge and the floating materialsare removed from the surface, for example by skimming, and both may bedisposed or processed further. The remaining liquid after primarytreatment may be discharged if sufficiently clean or, as is morecommonly the case, subjected to at least a secondary treatment.

A primary treatment system often includes one or more holding tanks,settling ponds, clarifiers or any other device or system that providesresidence time and allows the sludge and floating materials produced tobe separated from the liquid after the holding time. A pre-treatmentoperation also may be provided in which large objects may be removedfrom the wastewater, for example using a grate or large filter screen,prior to raw wastewater entering the primary treatment system.

Secondary treatment removes dissolved and suspended biological matter.Secondary treatment is typically performed by water-bornemicro-organisms in a managed habitat. The levels of important nutrientsfor the micro-organisms in the effluent from the primary treatment areimportant to the effective operation of the secondary treatment. If theamount of the nutrients are too low or the ratio of the nutrients issufficiently out of balance, the population of micro-organisms can beadversely affected and, in extreme cases, destroyed.

Some of the most important nutrients are carbon (C) and phosphorus (P)and maintaining the ratio of C—P in the primary treatment effluent is afactor when operating a wastewater treatment system that uses bothprimary and secondary treatment. While phosphorus is useful andeffective as a fertilizer, it can cause catastrophic problems if toomuch gets into streams, rivers, lakes and seas. When levels ofphosphates in water bodies are too high, it can trigger algal blooms andthen lead to depletion of oxygen levels. Fertilizers, human waste, anddetergents are the main sources of phosphate pollution. One personproduces an average of 2 g of phosphorus a day which ends up atmunicipal treatment works.

A secondary treatment system typically includes one or more holdingtanks, retention ponds, or clarifiers adapted to promote the growth andmaintenance of the micro-organisms and to allow sufficient contact withthe wastewater. Sometimes referred to as bio-reactors, the equipment isoften provided with superstructures or other components upon which someof the micro-organisms may be attached. In other systems, themicro-organism population is primarily or purely aqueous. In thesesystems some stirring or agitation may be provided such as by spargingair or oxygen into the holding vessel or using a mechanical stirringcomponent.

In addition, a tertiary treatment step is sometimes performed to reducethe levels of any remaining dissolved compounds to an acceptable levelfor discharge into the environment.

Primary treatment can be assisted through the addition of coagulants orother clarifying agents; however, in traditional treatment methods thesecoagulants and clarifying agents are rarely used because at thetreatment levels required for their effective use, they are noteconomically feasible. Clarifying agents can be used to remove suspendedsolids from liquids by inducing coagulation and/or flocculation (thesolids begin to aggregate forming flakes, which either precipitate tothe bottom or float to the surface of the liquid, and then they can beremoved or collected). The process of coagulation, along withflocculation, may be used whenever the natural settling rate ofsuspended material is too slow to provide effective clarification.Coagulants can be used to neutralize the charge of the suspended solids,bringing the particles together to create a small “pin floc”. Togenerate larger particles, or flocs, for faster settling, a highmolecular weight flocculant may be used, generally in combination with acoagulant.

Thus, effective methods of treating wastewater, including removingphosphorus waste while maintaining the ratio of C—P for the secondarytreatment stage using microorganisms, are important. Environmentallyfriendly and economical waste water treatment methods are generallydesirable.

SUMMARY

As disclosed herein, the present methods for treating wastewater includedosing wastewater, as part of a primary treatment system, with aclarifying agent of chloride salts of Ce and La having from 55.0-75.0%Ce and from 25.0-45.0% La and the balance being chloride salts of otherrare earth elements to obtain a rare earth concentration of 0.001 to 1.0mmol/L of wastewater.

The present methods for treating wastewater further include dosingwastewater, as part of a primary treatment system, with chloride saltsof Ce and La having from 55.0-75.0% Ce and from 25.0-45.0% La in anamount sufficient to achieve a ratio of C to P ranging from 200 C:1 P to25 C:1 P.

In additional embodiments these methods include dosing wastewater, aspart of a primary treatment system, with a clarifying agent of chloridesalts of a pure rare earth element to obtain a rare earth concentrationof 0.001 to 1.0 mmol/L of wastewater. As used herein, a “pure rare earthelement” is 95% or greater of that rare earth element, relative to totalmol of all other rare earth elements in the composition, the balancebeing chloride salts of other rare earth elements.

Further as disclosed herein is a method for treating wastewatercomprising dosing wastewater, as part of a primary treatment system,with a clarifying agent of chloride salts of a pure rare earth elementin an amount sufficient to achieve a ratio of C to P ranging from 200C:1 P to 25 C:1 P.

In an additional embodiment, the present methods include a method fortreating wastewater comprising dosing wastewater, as part of a primarytreatment system, with a clarifying agent of a mixture of chloride saltsof rare earth elements to obtain a rare earth concentration of 0.001 to1.0 mmol/L of wastewater, wherein the mixture is at least 95% of therare earth Ce and a rare earth selected from praseodymium (Pr),neodymium (Nd), promethium (Pm), samarium (Sm), yttrium (Y), andmixtures thereof.

In yet another embodiment, the present methods include a method fortreating wastewater comprising dosing wastewater, as part of a primarytreatment system, with a clarifying agent of a mixture of chloride saltsof rare earth elements to obtain a rare earth concentration of 0.001 to1.0 mmol/L of wastewater, wherein the mixture is at least 95% of therare earth La and a rare earth selected from praseodymium (Pr),neodymium (Nd), promethium (Pm), samarium (Sm), yttrium (Y), andmixtures thereof.

Further as disclosed herein are clarifying agents for use in the primarytreatment of wastewater comprising an aqueous solution of chloride saltsof the rare earth elements. The concentration of the solution of thechloride salt of the rare earth element can be 1.5 to 3.5 mol/L. Assuch, the clarifying agent comprises an aqueous solution of chloridesalts of a rare earth element or mixtures of rare earth elements havinga concentration of 1.5 to 3.5 mol/L. The pH of the solution can be 3 to4, and the density of the solution can be 1.3 to 1.6 g/mL. In oneembodiment these clarifying agents comprises an aqueous solution ofchloride salts of Ce and La having from 55.0-75.0% Ce and from25.0-45.0% La. In certain of these embodiments the balance of chloridesalts of other rare earth elements is less than 2%. And in certain ofthese embodiments common impurities selected from the group consistingof sodium, iron, lead, uranium, and mixtures thereof are present in anamount of less than approximately 10 g/L.

In a further embodiment, the present methods include a method fortreating wastewater comprising dosing wastewater, as part of a primarytreatment system, with a clarifying agent of a mixture of chloride saltsof rare earth elements to obtain a rare earth concentration of 0.001 to1.0 mmol/L of wastewater, wherein the mixture is CeCl₃ and LaCl₃ with25.0-35.0% Ce and 12.0-20.0% La and the balance being one or more ofchloride salts of the other rare earth elements. In certain of theseembodiments, the balance of chloride salts of other rare earth elementsis greater than 45% or is 50% or greater. The balance may be a singlerare earth chloride or chloride salts of a mixture of rare earthelements.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example plant flow with the RE clarifying agentdosed prior to the primary clarifier.

FIG. 2A is a graph of the settlable solids of each sample of Example 1Aas measured and plotted vs. the RE concentration in mmol/L.

FIG. 2B is a graph of the % reduction in settlable solids as calculatedand plotted vs the RE concentration in mmol/L of Example 1A.

FIG. 2C is a graph of unfiltered turbidity as measured and plotted vs.the RE concentration in mmol/L of Example 1A.

FIG. 2D is a graph of the % reduction in turbidity as calculated andplotted vs the RE concentration in mmol/L of Example 1A.

FIG. 2E is a graph of Total Phosphorus (TP) as measured and plotted vs.the RE concentration in mmol/L of Example 1A.

FIG. 2F is a graph of the % reduction in TP as calculated and plotted vsthe RE concentration in mmol/L of Example 1A.

FIG. 2G is a graph of Chemical Oxygen Demand (COD) as measured andplotted vs. the RE concentration in mmol/L of Example 1A.

FIG. 2H is a graph of the % reduction in COD as calculated and plottedvs the RE concentration in mmol/L of Example 1A.

FIG. 2I is a graph of Ortho-phosphate (OP) as measured and plotted vs.the RE concentration in mmol/L of Example 1A.

FIG. 2J is a graph of the % reduction in OP as calculated and plotted vsthe RE concentration in mmol/L of Example 1A.

FIG. 3A illustrates the plant flow of Example 3 with the RE clarifyingagent dosed prior to the primary clarifier.

FIG. 3B is a graph of Settlable Solids and phosphorus vs REconcentration in mmol/L as measured for Unfiltered TP, Filtered OP, andsettlable solids of Example 3 Test 1.

FIG. 3C is a graph of Settlable Solids and Turbidity, COD, BOD, and TOCvs RE concentration in mmol/L of Example 3 Test 1.

FIG. 3D is a graph of the % Reduction in Settlable Solids, Turbidity,Unfiltered TP, Filtered TP, COD, BOD, and TOC vs. the RE concentrationin mmol/L of Example 3 Test 1.

FIG. 3E is a graph of Settlable Solids and phosphorus vs REconcentration in mmol/L as measured for Unfiltered TP, Filtered OP, andsettlable solids of Example 3 Test 2.

FIG. 3F is a graph of Settlable Solids and Turbidity, COD, BOD, and TOCvs RE concentration in mmol/L of Example 3 Test 2.

FIG. 3G is a graph of the % Reduction in Settlable Solids, Turbidity,Unfiltered TP, Filtered TP, COD, BOD, and TOC vs. the RE concentrationin mmol/L of Example 3 Test 2.

FIG. 4 illustrates the plant flow of Example 4 with the RE clarifyingagent dosed after screening and prior to the small or large primaryclarifier, both of which are prior to the secondary clarifier.

FIG. 5A illustrates the plant flow of Example 5.

FIG. 5B is a graph of settlable solids, Unfiltered TP, and Filtered OPas measured plotted vs. the RE concentration in mmol/L of Example 5A.

FIG. 5C is a graph of turbidity, COD, BOD and TSS vs. the REconcentration in mmol/L of Example 5A.

FIG. 5D is a graph of the % Reduction of settable solids, turbidity,Unfiltered TP, Filtered OP, COD, BOD and TSS vs. the RE concentration inmmol/L of Example 5A.

FIG. 5E is a graph of settlable solids, Unfiltered TP, and Filtered OPas measured plotted vs. the RE concentration in mmol/L of Example 5B.

FIG. 5F is a graph of turbidity, COD, BOD and TSS vs. the REconcentration in mmol/L of Example 5B.

FIG. 5G is a graph of the % Reduction of settable solids, turbidity,Unfiltered TP, Filtered OP, COD, BOD and TSS vs. the RE concentration inmmol/L of Example 5B.

FIG. 5H is a graph of settlable solids, Unfiltered TP, and Filtered OPas measured plotted vs. the RE concentration in mmol/L of Example 5C.

FIG. 5I is a graph of turbidity, COD, BOD and TSS vs. the REconcentration in mmol/L of Example 5C.

FIG. 5J is a graph of the % Reduction of settable solids, turbidity,Unfiltered TP, Filtered OP, COD, BOD and TSS vs. the RE concentration inmmol/L of Example 5C.

FIG. 5K is a graph of settlable solids, Unfiltered TP, and Filtered OPas measured plotted vs. the RE concentration in mmol/L of Example 5D.

FIG. 5L is a graph of turbidity, COD, BOD and TSS vs. the REconcentration in mmol/L of Example 5D.

FIG. 5M is a graph of the % Reduction of settable solids, turbidity,Unfiltered TP, Filtered OP, COD, BOD and TSS vs. the RE concentration inmmol/L of Example 5D.

FIG. 5N is a graph of the settlable solids, Unfiltered TP and FilteredOP as measured plotted vs. the RE concentration in mmol/L of Example 5E.

FIG. 5O is a graph of turbidity and TSS vs. the RE concentration inmmol/L of Example 5E.

FIG. 5P is a graph of COD and BOD vs. the RE concentration in mmol/L ofExample 5E.

FIG. 5Q is a graph of the % Reduction of settable solids, turbidity,Unfiltered TP, Filtered OP, COD, BOD and TSS vs. the RE concentration inmmol/L for the room temperature samples of Example 5D.

FIG. 5R is a graph of the % Reduction of settable solids, turbidity,Unfiltered TP, Filtered OP, COD, BOD and TSS vs. the RE concentration inmmol/L for the chilled samples of Example 5D.

DETAILED DESCRIPTION

Before the rare earth (RE) clarifying agents and methods are disclosedand described, it is to be understood that this disclosure is notlimited to the particular structures, process steps, or materialsdisclosed herein, but is extended to equivalents thereof as would berecognized by those ordinarily skilled in the relevant arts. It shouldalso be understood that terminology employed herein is used for thepurpose of describing particular embodiments only and is not intended tobe limiting. It must be noted that, as used in this specification, thesingular forms “a,” “an,” and “the” include plural referents unless thecontext clearly dictates otherwise. Thus, for example, reference to “acerium chloride” is not to be taken as quantitatively or sourcelimiting, reference to “a step” may include multiple steps, reference to“producing” or “products” of a reaction or treatment should not be takento be all of the products of a reaction/treatment, and reference to“treating” may include reference to one or more of such treatment steps.As such, the step of treating can include multiple or repeated treatmentof similar materials/streams to produce identified treatment products.

The present application relates to rare earth clarifying agents andmethods of using these rare earth clarifying agents in the primarytreatment of wastewater. As used herein, primary treatment includesholding the wastewater in one or more holding tanks, settling ponds,clarifiers, or the like that provides residence time and allows theheavy solids to settle to the bottom while oil and lighter solids tofloat to the surface. The settlable solids can be removed as sludge andthe floating materials are also removed. As described herein, inaddition to separation by flotation and sedimentation in the primarytreatment, the rare earth clarifying agents are added as part of theprimary treatment process.

The rare earth clarifying agents are added or dosed at any point withinthe primary treatment system, including upstream of the primarytreatment operation, within the primary treatment operation, or bothupstream of and within the primary treatment operation. As such, dosingin the primary treatment system or dosing as part of a primary treatmentsystem means that the rare earth clarifying agents are added or dosed atany point upstream of the primary treatment operation, within theprimary treatment operation, or both upstream of and within the primarytreatment operation.

It has been determined that chloride salts of certain rare earthelements have beneficial effects as clarifying agents in the primarytreatment of wastewater. As such, as used herein rare earth clarifyingagents are chloride salts of rare earth elements. Chloride salts having25% or more (by mol of rare earth element relative to total mol of allrare earth elements in the salt composition) of rare earth elements maybe particularly attractive. These rare earth elements include all of therare earth elements individually, as well as mixtures thereof. Incertain embodiments, certain mixtures may be particularly attractive andin yet other embodiments, the light rare earth elements and mixturesthereof are particularly attractive.

As disclosed herein, the clarifying agents are typically an aqueoussolution of chloride salts of the rare earth elements, eitherindividually or mixtures thereof.

Without being held to any particular theory, it is believed that therare earth clarifying agents and treatment methods described hereinreduce both P and C in the primary treatment, but appear to reduce Ppreferentially over C. Thus, it appears that the rare earth clarifyingagents can beneficially adjust the C—P ratio in the primary treatmentfor typical wastewaters especially sewage, because the rare earthclarifying agents reduce P more than C and typical wastewaters have aC—P ratio with relatively more P than desirable.

The rare earth clarifying agents and treatment methods described hereinalso beneficially can reduce one or more of turbidity, orthophosphate(OP), total phosphorous (TP), total organic carbon (TOC), chemicaloxygen demand (COD), biochemical oxygen demand (BOD), and totalsuspended solids (TSS). The rare earth clarifying agents and treatmentmethods described herein further beneficially can increase the settlablesolids. Since water clarity is improved (i.e., turbidity is decreasedand settlable solids are increased), the rare earth clarifying agentsalso improve initial solid-liquid separation.

The clarifying agents as disclosed herein are chloride salts of rareearth elements. The rare earth elements (REE) are a group of seventeenmetallic elements—the fifteen lanthanides, with atomic numbers 57(lanthanum, La) to 71 (lutetium, Lu), together with yttrium (Y, atomicnumber 39) and scandium (Sc, atomic number 21).

Specifically, the rare earth elements (REE) are cerium (Ce), dysprosium(Dy), erbium (Er), europium (Eu), gadolinium (Gd), holmium (Ho),lanthanum (La), lutetium (Lu), neodymium (Nd), praseodymium (Pr),promethium (Pm), samarium (Sm), scandium (Sc), terbium (Tb), thulium(Tm), ytterbium (Yb) and yttrium (Y). As used herein the rare-earthelements are selected from the group consisting of cerium (Ce),dysprosium (Dy), erbium (Er), europium (Eu), gadolinium (Gd), holmium(Ho), lanthanum (La), lutetium (Lu), neodymium (Nd), praseodymium (Pr),promethium (Pm), samarium (Sm), scandium (Sc), terbium (Tb), thulium(Tm), ytterbium (Yb), yttrium (Y), and mixtures thereof. As describedherein the light rare earth elements include cerium (Ce), lanthanum(La), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm),and mixtures thereof.

Because of their chemical similarities, REE tend to occur together inminerals and rocks and they can be difficult to separate from eachother. Geologically occurring compounds tend to be oxides, halides(fluorides), carbonates, phosphates, silicates, and fluorocarbonates. Asused herein, the REE are chlorides.

It also may be possible to recycle REE from previous uses, such as highperformance magnets, batteries, used electronics, and coal and coalby-products.

As used herein, the rare earth clarifying agents can be compositionscontaining a singular rare earth element or a mixture of rare earthelements. The rare earth clarifying agents can be aqueous solutions of asingle rare earth element chloride salt or aqueous solutions of amixture of rare earth elements chloride salts.

For the purposes of this application, % of a rare earth element isrelative to total mol of all rare earth elements in the salt compositionwithout regard to the chloride anion or any other trace salts ofnon-rare earth elements that may be included in a composition such asNaCl. Common impurities found in rare earth chlorides as utilized hereininclude sodium, iron, lead, and uranium. In certain embodiments the rareearth clarifying agents contain less than approximately 10 g/L of thesecommon impurities. The rare earth clarifying agents can include lessthan approximately 9 g/L of sodium, less than approximately 20 mg/Liron, less than approximately 3 mg/L lead, and less than approximately 1mg/L uranium.

In one embodiment, clarifying agents of chloride salts of pure rareearth elements have been tested and found to be effective. As usedherein, a “pure rare earth element” is 95% or greater of that rare earthelement, relative to total mol of all other rare earth elements in thecomposition, the balance being chloride salts of other rare earthelements. As such, the clarifying agents comprise an aqueous solution ofchloride salts of the pure rare earth element.

For example, pure cerium is 95% or greater cerium; pure lanthanum is 95%or greater lanthanum; pure neodymium is 95% or greater neodymium; puresamarium is 95% or greater samarium; pure yttrium is 95% or greateryttrium; and the like. In some embodiments a “pure rare earth element”may be 99% or greater of that rare earth element, relative to total molof all other rare earth elements in the composition, the balance beingchloride salts of other rare earth elements. For example, the clarifyingagent may be chloride salts of 99% or greater cerium.

In another embodiment, the clarifying agents of chloride salts of purerare earth elements can be selected from the group consisting oflanthanum (La), praseodymium (Pr), neodymium (Nd), promethium (Pm),samarium (Sm), and yttrium (Y).

In another embodiment, the clarifying salt for use in wastewatertreatment is a rare earth chloride salt of Ce having from 95-100% Ce byweight (relative to the total mass of rare earth elements) and thebalance being chloride salts of other rare earth elements. Inparticular, this embodiment includes rare earth chloride salts havingCeCl₃ with the 95.000-99.999% Ce (again, relative to the total mass ofrare earth elements in the salt) and the balance being one or more ofchloride salts of the other rare earth elements.

The rare earth clarifying agents also can be chloride salts of a mixtureof rare earth elements. In one embodiment, the clarifying salt for usein wastewater treatment is a rare earth chloride salt of a mixture of Ceand La. As such, the clarifying agents comprise an aqueous solution ofchloride salts of these mixtures of rare earth elements.

In one embodiment, the clarifying salts for use in wastewater treatmentare rare earth chloride salts of Ce and La having from 55.0-75.0% Ce andfrom 25.0-45.0% La and the balance being chloride salts of other rareearth elements. As such, the clarifying agent comprises an aqueoussolution of chloride salts of Ce and La having from 55.0-75.0% Ce andfrom 25.0-45.0% La. In certain embodiments this balance of chloridesalts of other rare earth elements is less than 2%. In certain of theseembodiments common impurities selected from the group consisting ofsodium, iron, lead, uranium, and mixtures thereof are present in anamount of less than approximately 10 g/L.

In particular, embodiments include rare earth chloride salts having amixture of CeCl₃ and LaCl₃ with the 60.0-65.0% Ce and 30.0-40.0% La andthe balance being one or more of chloride salts of the other rare earthelements. Chloride salts of 59.8-70.1% Ce and 29.9-40.1% La, of63.0-69.0% Ce and 30.0-36.0% La, and of 63.0-68.0% Ce and 31.0-35.0% La(all with the balance being one or more of chloride salts of the otherrare earth elements) are all further embodiments of the Ce/La clarifyingsalt. In certain embodiments the balance of chloride salts of other rareearth elements is less than 2% and in certain of these embodimentscommon impurities selected from the group consisting of sodium, iron,lead, uranium, and mixtures thereof are present in an amount of lessthan approximately 10 g/L.

In embodiments in which the clarifying salts for use in wastewatertreatment are rare earth chloride salts of Ce and La having from55.0-75.0% Ce and from 25.0-45.0% La and the balance being chloridesalts of other rare earth elements, the other rare earth elements may beany one or more of the other rare earth elements. These other rare earthelements may be selected from the group consisting of Pr, Nd, Sm, Y, andmixtures thereof.

Embodiments also include rare earth chloride salts having a mixture ofCeCl₃ and LaCl₃ with 25.0-35.0% Ce and 12.0-20.0% La and the balancebeing one or more of chloride salts of the other rare earth elements. Incertain of these embodiments, the balance of chloride salts of otherrare earth elements is greater than 45% or is 50% or greater. Thebalance may be a single rare earth chloride or chloride salts of amixture of rare earth elements. For example the balance of chloridesalts may be 50% Y, or 50% Sm, or a mixture of 25% Sm and 25% Y.

In an embodiment, the clarify salt may be provided in hydrated crystalform (e.g., RECl₃·xH₂O) as described in the examples.

In other embodiments, the clarifying salt for use in wastewatertreatment is a rare earth chloride salt mixture, wherein the mixture is95% or greater of the rare earth Ce and a rare earth selected frompraseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm),yttrium (Y), and mixtures thereof. For example, the mixture is 95% orgreater of Ce and praseodymium (Pr), by way of example, 50% Ce and 45%Pr or 80% Ce and 15% Pr.

In another embodiment, the clarifying salt for use in wastewatertreatment is a rare earth chloride salt mixture, wherein the mixture is95% or greater of the rare earth La and a rare earth selected frompraseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm),yttrium (Y), and mixtures thereof. For example, the mixture is 95% orgreater of La and praseodymium (Pr), by way of example, 50% La and 45%Pr or 80% La and 15% Pr.

In another embodiment, the clarifying salt for use in wastewatertreatment is a rare earth chloride salt mixture, wherein the mixture is95% or greater of the rare earth mixture Pr and a rare earth selectedfrom cerium (Ce), neodymium (Nd), promethium (Pm), samarium (Sm),yttrium (Y), and mixtures thereof. In another embodiment, the clarifyingsalt for use in wastewater treatment is a rare earth chloride saltmixture, wherein the mixture is 95% or greater of the rare earth mixturePr and a rare earth selected from lanthanum (La), neodymium (Nd),promethium (Pm), samarium (Sm), yttrium (Y), and mixtures thereof.

In another embodiment, the clarifying salt for use in wastewatertreatment is a rare earth chloride salt mixture, wherein the mixture is95% or greater of the rare earth mixture Nd and a rare earth selectedfrom cerium (Ce), praseodymium (Pr), promethium (Pm), samarium (Sm),yttrium (Y), and mixtures thereof. In yet another embodiment, theclarifying salt for use in wastewater treatment is a rare earth chloridesalt mixture, wherein the mixture is 95% or greater of the rare earthmixture Nd and a rare earth selected from lanthanum (La), praseodymium(Pr), promethium (Pm), samarium (Sm), yttrium (Y), and mixtures thereof.

In another embodiment, the clarifying salt for use in wastewatertreatment is a rare earth chloride salt mixture, wherein the mixture is95% or greater of the rare earth mixture Pm and a rare earth selectedfrom cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm),yttrium (Y), and mixtures thereof. In yet another embodiment, theclarifying salt for use in wastewater treatment is a rare earth chloridesalt mixture, wherein the mixture is 95% or greater of the rare earthmixture Pm and a rare earth selected from lanthanum (La), praseodymium(Pr), neodymium (Nd), samarium (Sm), yttrium (Y), and mixtures thereof.

In another embodiment, the clarifying salt for use in wastewatertreatment is a rare earth chloride salt mixture, wherein the mixture is95% or greater of the rare earth mixture Sm and a rare earth selectedfrom cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm),yttrium (Y), and mixtures thereof. In yet another embodiment, theclarifying salt for use in wastewater treatment is a rare earth chloridesalt mixture, wherein the mixture is 95% or greater of the rare earthmixture Sm and a rare earth selected from lanthanum (La), praseodymium(Pr), neodymium (Nd), promethium (Pm), yttrium (Y), and mixturesthereof.

In another embodiment, the clarifying salt for use in wastewatertreatment is a rare earth chloride salt mixture, wherein the mixture is95% or greater of the rare earth mixture Y and a rare earth selectedfrom cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm),samarium (Sm), and mixtures thereof. In yet another embodiment, theclarifying salt for use in wastewater treatment is a rare earth chloridesalt mixture, wherein the mixture is 95% or greater of the rare earthmixture Y and a rare earth selected from lanthanum (La), praseodymium(Pr), neodymium (Nd), promethium (Pm), samarium (Sm), and mixturesthereof.

Treatment Method

As described herein, the clarifying agents are utilized as part of awastewater treatment method and as such, are added at any point in thetreatment system upstream of and including in the primary treatmentoperation itself. As defined herein, “dosing as part of a primarytreatment system” means dosing the wastewater with the rare earthclarifying agent upstream of and/or in the primary treatment operation.As such, the methods for treating wastewater include dosing thewastewater with the rare earth clarifying agent upstream of the primarytreatment operation, in the primary treatment operation, or bothupstream of and in the primary treatment operation. When added upstreamof the primary treatment operation, the methods for treating wastewaterinclude dosing the wastewater with the rare earth clarifying agent priorto any pretreatment or grit screen.

Adding the rare earth clarifying agents in or prior to the primarytreatment beneficially may adjust the C—P ratio. The beneficial resultsof dosing the rare earth clarifying agents at this point in thetreatment process is also of note because coagulants/clarifying agentsare not typically dosed during this part of the water treatment process.The rare earth clarifying agents are cost effective because their doserates are relatively small and they are highly effective in adjustingthe C—P ratio. They can also be effective in reducing one or more ofturbidity, orthophosphate (OP), total phosphorous (TP), total organiccarbon (TOC), chemical oxygen demand (COD), biochemical oxygen demand(BOD), and total suspended solids (TSS), and increasing settlablesolids.

The rare earth clarifying agents may be dosed in a single addition ormultiple additions. When multiple additions are utilized, the rare earthclarifying agents may be dosed multiple times at the same dose pointwithin or just prior to the primary treatment operation or the rareearth clarifying agents may be dose at multiple dose points within orjust prior to the primary treatment operation. In a plant runningcontinuously, multiple dose points may be advantageous.

FIG. 1 is a flow chart for an embodiment of a method for treatingwastewater with a rare earth element clarifying agent. In the method100, the raw wastewater is first optionally passed through apre-treatment operation 102. The pre-treatment operation 102 may includeany pre-treatments to remove large objects, such as for example passingthe raw wastewater through a grate, through a knockout tank, or otherphysical screen separator.

The pre-treated water is then dosed with the rare earth elementclarifying agent in a rare earth dosing operation 104 before it ispassed into the primary treatment system where it undergoes primarytreatment in the primary treatment operation 106. The rare earth dosingoperation 104 injects, mixes, or otherwise adds the rare earth elementclarifying agent to the wastewater so that some concentration of rareearth elements is obtained in the wastewater during the primarytreatment operation 106. In an embodiment, the dosing rate is changed tomaintain a particular target concentration. Alternatively, the dosingrate may be set based on the observed performance of the primarytreatment system (and secondary treatment system) and not adjustedunless degraded performance is observed. For example, it has beenobserved that if a dose is too high, the resulting sludge becomes toothick to be efficiently removed from the primary treatment system andthe primary treatment effluent becomes too clear and reduced innutrients, causing the micro-organism population in the secondarytreatment to starve unless supplemental nutrients are provided. In yetanother embodiment, the dosing rate of the rare earth element clarifyingagent may be adjusted based on measurements of some indirect indicatorparameter such as total organic carbon (TOC), chemical oxygen demand(COD), filtered orthophosphate (FOP), unfiltered orthophosphate (UOP),total phosphorus (TP), turbidity, and Biochemical Oxygen Demand (BOD).The dosing rate that may be used is described in greater detail below.

Depending on the embodiment, the rare earth element clarifying agent maybe continuously added at a desired rate or discrete amounts may be addedbatch-wise. A single dose point or multiple dose points may be utilized.If added in discrete amounts, the rare earth element clarifying agentmay be added in a single addition or in multiple additions, for examplein one to twenty discrete additions and in certain embodiments in one toten discrete additions. These additions may be at the same dose point orat different dose points.

Furthermore, the rare earth element clarifying agent may be added at anypoint in the treatment system upstream of and including in the primarytreatment operation itself. When added upstream of the primary treatmentoperation, the methods for treating wastewater include dosing thewastewater with the rare earth clarifying agent prior to anypretreatment. For example, in one system configuration, the dosingoperation 104 is performed using a simple metering pump set to inject apredetermined amount of the rare earth element clarifying agent into thewastewater stream as it enters the primary treatment system. In analternate embodiment, the rare earth element clarifying agent may beadded directly to primary treatment operation (e.g., directly into theclarifier, holding tank, etc.). In yet another embodiment, the rareearth element clarifying agent may be added before the pre-treatment ofthe wastewater. If multiple dose points are utilized, these multipledose points may be one of these locations at any point in the treatmentsystem upstream of and including in the primary treatment operationitself or may include all of these locations.

The primary treatment operation 106 includes retaining the wastewaterand rare earth element clarifying agent for a retention time (residencetime), thereby allowing flocculation and/or coagulation time to occurresulting in separation of solids from the wastewater. As mentionedabove, a typical form of wastewater treatment is to flow the wastewaterthrough a clarifier, settling tank, or other holding vessel and controlthe flow rates that results in a predetermined residence time.Clarifiers are settling tanks provided with mechanical equipment forcontinuous removal of solids being deposited by sedimentation as sludge.A clarifier is designed to more efficiently remove solid particulates orsuspended solids from liquid for clarification and (or) thickening thana simple settling tank.

In the flow chart shown in FIG. 1, the primary treatment is followed bya secondary treatment operation 108. Secondary treatment, as describedabove, involves the biological treatment of the dissolved and suspendedorganic material as well as the nutrients nitrogen and phosphorus, and,optionally, disinfection to kill pathogenic bacteria. As describedherein, the wastewater may be dosed with the rare earth clarifying agentin an amount sufficient to obtain a ratio of C to P ranging from 500 C:1P to 5 C:1 P, and in some embodiments 200 C:1 P to 25 C:1 P, so that thesecondary treatment operates more efficiently. In certain embodiments,the wastewater may be dosed with the rare earth clarifying agent in anamount sufficient to obtain a ratio of C to P ranging from 100 C:1 P to50 C:1 P. Wastewater prior to treatment may have a C to P ratio ofapproximately 20 C:1 P and the methods as described herein can adjustthat wastewater such that the C:P ratio is approximately 100 C:1 P to 50C:1 P and thus the secondary treatment operates more efficiently.

After the secondary treatment, the treated effluent may be discharged ina discharge operation 110 or subjected to additional treatment (e.g.,tertiary treatment, not shown). As shown in the Examples, below, theaddition of the rare earth element clarifying agent improves theperformance of the primary treatment in terms of increased mass ofsolids removal and improved phosphorous removal while maintaining anacceptable C—P ratio. The addition of the rare earth clarifying agentsalso beneficially may reduce one or more of turbidity, orthophosphate(OP), total phosphorous (TP), total organic carbon (TOC), chemicaloxygen demand (COD), biochemical oxygen demand (BOD), and totalsuspended solids (TSS), and further beneficially may can increase thesettlable solids.

Rare Earth Element Treatment Levels

In one embodiment of the method 100, the rare earth element treatmentlevel to be obtained in the dosing operation 104 is based on the amountof rare earth elements (in mmol of total rare earth elements or mol RE)per liter (L) of wastewater. In this embodiment, the dosing rate of therare earth element clarifying agent is varied based on the wastewaterstream's volumetric flowrate to achieve a predetermined concentrationtarget of mmol/L of rare earth elements to liter of wastewater.

The concentration of the solution of the chloride salt of the rare earthelement also can be adjusted to achieve the target concentration ofmmol/L of rare earth elements to liter of wastewater or the dosingamount (volume of the solution of the chloride salt of the rare earthelement) can be varied to achieve the target concentration of mmol/L ofrare earth elements to liter of wastewater.

The concentration of the solution of the chloride salt of the rare earthelement can be 1.5 to 3.5 mol/L and in some embodiments 1.8 to 2.6mol/L. As such, the clarifying agent comprises an aqueous solution ofchloride salts of a rare earth element or mixtures of rare earthelements having a concentration of 1.5 to 3.5 mol/L. The pH of thesolution can be 3 to 4. The density of the solution can be 1.3 to 1.6g/mL. The treatment is focused to achieve a target concentration ofmmol/L of rare earth elements to liter of wastewater.

In one embodiment the range of the concentration target is from 0.001 to1.0 mmol RE/L wastewater. In another the concentration target is from0.01 to 0.5 mmol RE/L wastewater. In a yet more narrow embodiment theconcentration target is from 0.03 to 0.30 mmol RE/L wastewater. As such,the methods for treating wastewater described herein, include dosingwastewater with a clarifying agent of chloride salts of a pure rareearth element to obtain a rare earth concentration of 0.001 to 1.0mmol/L of wastewater, and in certain embodiments 0.01 to 0.5 mmol ofwastewater or 0.03 to 0.30 mmol/L wastewater. The methods for treatingwastewater described herein, further include dosing wastewater with aclarifying agent of chloride salts of a mixture of rare earth elementsto obtain a rare earth concentration of 0.001 to 1.0 mmol/L ofwastewater, and in certain embodiments 0.01 to 0.5 mmol of wastewater or0.03 to 0.30 mmol/L wastewater. This mixture can be any mixtures of rareearth elements, including those specifically detailed herein.

This dosing target may be used regardless of whether the rare earthelement clarifying agent is a pure rare earth element or a mixture ofrare earth elements. This dosing target may be achieved by a single doseor by multiple doses which together provide the dosing target. Ifmultiple doses are utilized, the multiple doses can be performed at thesame site or at different sites.

In an alternative embodiment, the rare earth element treatment level tobe obtained in the dosing operation 104 is based on achieving a targetratio of carbon to phosphorus (C—P) in the primary treatment effluent.In this embodiment, the wastewater is dosed with the rare earth elementclarifying agents in an amount sufficient to achieve ratio of C to Pranging from 500 C:1 P to 5 C:1 P and in certain instances 200 C:1 P to25 C:1 P. In other embodiments, a C to P of 200 C:1 P to 30 C:1 P or 200C:1 P to 35 C:1 P or 200 C:1 P to 40 C:1 P or 200 C:1 P to 45 C:1 P canbe achieved. More narrowly, the target C—P ratio may range from 150 C:1P to 25 C:1 P or even ranging from approximately 100 C:1 P to 50 C:1 P.Wastewater prior to treatment can have a C to P ratio of approximately20 C:1 P and the methods as described herein can adjust the C:P ratio toapproximately 100 C:1 P to 50 C:1 P.

EXAMPLES

The description and results of experiments showing the efficacy of therare earth element clarifying agent and the treatment method aredescribed in the following non-limiting examples. It is noted that someof the mass values are reported in mass of rare earth oxide (REO). Thisis used because the RECl₃ hydrate has some inherent variability in thehydration levels which makes calculation of mass of RECl₃ hydrate a poormetric in some instances. Conversion of RECl₃ hydrate to REO istypically handled by burning/oxidizing all RECl₃ hydrate to REO as isknown in the art.

Example 1: Experimental Data Generated from Simulated Wastewater

Synthesis of Rare Earth Chloride Solution:

Individual RECl₃ solutions were prepared by dissolving rare earth oxideswith at least 99.9% purity of the individual rare earth vs the otherrare earths in concentrated hydrochloric acid (HCl). A concentration of2 mol/L RE was targeted. The solution was then pH adjusted with diluteNaOH until the pH was between 3 and 4. The solutions were then titratedwith 0.1 M EDTA using Xylenol Orange as an indicator to determine theactual concentration. As an example, 32.74 g of La₂O₃ (99.9% La vs allRE) was dissolved in a minimal amount of conc HCl. The solution was thenpH adjusted with dilute NaOH solution. The volume was adjusted to 100 mlby dilution with DI water. The resulting solution was titrated and foundto be 1.95 mol/L La.

Mixtures of RECl₃ solutions were prepared by mixing the appropriatevolumes of the individual RECl₃ solutions such that the desired REdistribution was obtained. As an example, to prepare a 66.67% Ce, 33.33%La solution, 1 ml of 2.43 mol/L Ce solution was mixed with 0.625 ml of1.95 mol/L La.

Simulated Wastewater:

Simulated wastewater was created using a combination of threecomponents 1) simulated human feces, 2) simulated human urine, and 3)food waste. Methods for preparing simulated human feces and urine wereobtained from the literature. (See Colón, J.; Forbis-Stokes, A. A.;Deshusses, M. A. Anaerobic digestion of undiluted simulant human excretafor sanitation and energy recovery in less-developed countries. Energyfor Sustainable Development 29 (2015) 57-64.) The food waste formula wasobtained from the 2014 ASCE Mid-Pacific Conference Water TreatmentCompetition Rules.

The amounts of simulated human feces and urine were based on publishednumbers for the amount of feces and urine generated per person per day.These numbers were cross referenced with known flow rates for plantswhich treat known populations. The food waste was added in amounts toincrease the total phosphorus and chemical oxygen demand to levelscomparable to observed levels in WWT plants.

Simulated feces Simulated urine Ingredient Amount (g/kg) IngredientAmount (g/L) Water 800 Urea 9.3 Baker’s yeast (dry) 60 Creatinine 2.0Microcrystalline 20 Ammonium 1.0 cellulose citrate Psyllium 35 NaCl 8Miso paste 35 KCl 1.65 Oleic acid 40 KHSO₄ 0.5 NaCl 4 MgSO₄ 0.2 KCl 4KH₂PO₄ 1.75 CaCl₂ 2 KHCO₃ 0.5

A reasonable average of feces generated per day is 350-400 g/day/personand for urine it is 1 L/day/person (reference 1).

The amount of wastewater generated per day can vary. The USGS states itis 100 gallons/day/person. The EPA published a paper in 1993 statingthat the amount of wastewater generated was 184 gallons/day/person.

For this experiment, a generated wastewater average of 200gal/day/person was chosen along with 400 g/day/person for feces and 1L/day/person for urine. Thus, for 1 gal of test solution: 2 g ofsimulated feces were used and 5 ml of simulated urine.

The food waste formula, obtained from the 2014 ASCE Mid-PacificConference Water Treatment Competition Rules as set forth below, wasused. These ingredients were mixed together (excluding the Simple GreenAll-Purpose Cleaner and water) and blended to form a consistent mixture.

Ingredient Quantity per 4.5 gallons Tostitos Original Tortilla Chips 4oz Ortega Thick & Chunky Medium Salsa 1 cup Goya black beans 7.5 oz (½can) Shredded mild cheddar cheese 2 oz Iceberg lettuce 1 head, heartremoved, cut into quarter shredded into ¼ inch stripes along the shortside Coca-Cola Classic 6 oz Nabisco saltines, roughly crushed ⅛ lb into1 inch pieces (max) Ocean Spray Cranberry Juice 2 cups Sun-maid blackseedless raisins ½ cup Quaker steel cut oats 1 cup Yoplait originalstrawberry yogurt 3 oz Simple Green All-Purpose Cleaner ¼ cup

Thus, the simulated waste water was made by charging a 5 gal bucketfitted with baffles, overhead stirrer, and discharge valve near thebottom with 8 g simulated feces, 11 ml simulated human urine, 5 g foodwaste mixture, and 1.5 ml Simple Green All-Purpose Cleaner per 1 gal oftap water (City of Orange, Calif.).

Results and Experimental Example 1A: Dose Curves

A RECl₃ solution was made at the concentrations outlined in the tablebelow. 4 gal of simulated wastewater was made as described above andallowed to stir for at least 15 min. A 1 L sample was collected in anImhoff cone from the discharge valve as a control. Rare earth chloridewas then dosed into the simulated wastewater solution in increments suchthat the RE concentration in the mixture increased by approximately0.013 mmol/L each increment for a total of 9 additions. The actualconcentration was calculated based on the dose and the volume of sampleremoved after sampling. The mixture was allowed to stir for at least 5min before a 1 L sample was collected as before. This process wasrepeated until a total of 10 samples (1 control and 9 additions) werecollected. The pH of the mixture was recorded when each sample wastaken. Each 1 L sample was allowed to settle according to the standardSettable Solids measurement procedure. After 1 hr the volume of settablesolids was recorded and a filtered and unfiltered sample of thesupernatant was collected. Filtered samples were filtered through a 0.45micron syringe filter and analyzed for ortho-phosphorus. Unfilteredsamples were analyzed for turbidity, total phosphorus, and chemicaloxygen demand.

RE concen- Rare Earth tration Chloride RE Distribution (mol/L) CeCl₃≥99.9% Ce 2.43 SmCl₃ ≥99.9% Sm 1.47 YCl₃ ≥99.9% Y 3.13 (CeLa)Cl₃ 66.6%Ce, 33.3% La 2.11 (CeLaY)Cl₃ 33.3% Ce, 16.6% La, 50% Y 2.61 (CeLaSm)Cl₃33.3% Ce, 16.6% La, 50% Sm 1.77 (CeLaSmY)Cl₃ 33.3% Ce, 16.6% La, 25% Sm,25% Y 2.11

The settlable solids of each sample were measured and plotted vs. the REconcentration in mmol/L, as shown in FIG. 2A. The % reduction insettlable solids was also calculated and plotted, as shown in FIG. 2B.Unfiltered samples of the supernatant from each dosing were measured forturbidity and this was plotted vs. the RE concentration in mmol/L, asshown in FIG. 2 C. The % reduction in turbidity was also calculated andplotted, as shown in FIG. 2D.

Unfiltered samples of the supernatant from each dosing were measured forTotal Phosphorus (TP) and this was plotted vs. the RE concentration inmmol/L, as shown in FIG. 2E. The % reduction in TP was also calculatedand this was plotted, as shown in FIG. 2F. Unfiltered samples of thesupernatant from each dosing were measured for Chemical Oxygen Demand(COD) and this was plotted vs. the RE concentration in mmol/L, as shownin FIG. 2G. The % reduction in COD was also calculated and plotted, asshown in FIG. 2H.

Unfiltered samples of the supernatant from each dosing were measured forOrtho-phosphate (OP) and this was plotted vs. the RE concentration inmmol/L, as shown in FIG. 2I. The % reduction in OP was also calculatedand plotted, as shown in FIG. 2J.

Example 1B: Single Dose Single RE (0.241 Mmol/L RE Dose)

A RECl₃ solution was made at the concentrations outlined in the tablebelow via the method outlined above. 4 gal of simulated wastewater wasmade as outlined above and allowed to stir for at least 15 min. 10Imhoff cones were set up and 8 were charged with the appropriate amountof a RECl₃ solution such that the final concentration was 0.241 mmol/LRE (except for the CeLa mixture which was 0.225 mmol/L). Two cones wereleft as control samples. The order of the 15 RE used and the placementof the 2 controls was randomized. The 10 Imhoff cones were then loadedwith simulated wastewater from the discharge valve. Each 1 L sample wasallowed to settle according to the standard Settable Solids measurementprocedure. After 1 hr the volume of settable solids was recorded and afiltered and unfiltered sample of the supernatant was collected.Filtered samples were filtered through a 0.45 micron syringe filter andanalyzed for ortho-phosphorus. Unfiltered samples were analyzed forturbidity, total phosphorus, chemical oxygen demand (COD), andbiochemical oxygen demand (BOD). This process was repeated with theremaining RE solutions. The 2 controls in each run were averaged andcompared to the results within each run.

RE Volume RE concentration Rare Earth RE concentration added in treatedwater Chloride Distribution (mol/L) (ml) (mmol/L) YCl₃ ≥99.9% Y 3.130.077 0.241 LaCl₃ ≥99.9% La 1.95 0.124 0.241 CeCl₃ ≥99.9% Ce 2.43 0.0990.241 PrCl₃ ≥99.9% Pr 1.85 0.130 0.241 NdCl₃ ≥99.9% Nd 1.89 0.127 0.241SmCl₃ ≥99.9% Sm 1.47 0.164 0.241 EuCl₃ ≥99.9% Eu 1.73 0.140 0.241 GdCl₃≥99.9% Gd 1.53 0.157 0.241 TbCl₃ ≥99.9% Tb 1.94 0.124 0.241 DyCl₃ ≥99.9%Dy 1.99 0.121 0.241 HoCl₃ ≥99.9% Ho 2.04 0.118 0.241 ErCl₃ ≥99.9% Er1.97 0.122 0.241 TmCl₃ ≥99.9% Tm 2.84 0.085 0.241 YbCl₃ ≥99.9% Yb 1.990.121 0.241 LuCl₃ ≥99.9% Lu 1.97 0.122 0.241 (CeLa)Cl₃ 66.67% Ce, 2.250.100 0.225 33.33% LaRun 1

Settlable Filtered solids Turbidity OP TP COD BOD RECl₃ (ml/L) (FAU)(mg/L) (mg/L) (mg/L) (mg/L) Control 5.5 167 2.3 3.9 550 316 EuCl₃ 7.5141 0.1 3.3 450 175 TbCl₃ 6.5 149 0.14 3.6 480 190 NdCl₃ 7.5 131 0.083.3 430 259 DyCl₃ 6.0 155 0.2 3.5 490 224 PrCl₃ 7.5 130 0.06 3.2 450 194Control 5.0 173 2.3 3.6 540 270 CeCl₃ 5.5 145 0.06 3.3 410 233 SmCl₃ 6.0152 0.1 3.4 460 204 GdCl₃ 6.5 140 0.1 2.9 430 197Run 2

Settlable Filtered solids Turbidity OP TP COD BOD RECl₃ (ml/L) (FAU)(mg/L) (mg/L) (mg/L) (mg/L) ErCl₃ 6.0 155 0.14 3.1 480 218 Control 5.0168 2.2 3.4 510 286 Control 5.0 169 2.2 3.5 530 247 LuCl₃ 5.0 156 0.23.4 490 247 LaCl₃ 6.5 122 0 3.1 420 202 HoCl₃ 5.0 160 0.26 3.4 480 191(CeLa)Cl₃ 5.5 141 0.04 3.3 440 224 TmCl₃ 5.0 166 0.12 3.3 470 180 YCl₃5.0 154 0.08 3.4 470 189 YbCl₃ 5.0 153 0.16 3.3 470 182Difference from Control (Average of Controls−Dose Value)

Settlable Filtered solids Turbidity OP TP COD BOD RECl₃ (ml/L) (FAU)(mg/L) (mg/L) (mg/L) (mg/L) YCl₃ 0 14.5 2.12 0.05 50 77.5 LaCl₃ −1.546.5 2.2 0.35 100 64.5 CeCl₃ −0.25 25 2.24 0.45 135 60 PrCl₃ −2.25 402.24 0.55 95 99 NdCl₃ −2.25 39 2.22 0.45 115 34 SmCl₃ −0.75 18 2.2 0.3585 89 EuCl₃ −2.25 29 2.2 0.45 95 118 GdCl₃ −1.25 30 2.2 0.85 115 96TbCl₃ −1.25 21 2.16 0.15 65 103 DyCl₃ −0.75 15 2.1 0.25 55 69 HoCl₃ 08.5 1.94 0.05 40 75.5 ErCl₃ −1 13.5 2.06 0.35 40 48.5 TmCl₃ 0 2.5 2.080.15 50 86.5 YbCl₃ 0 15.5 2.04 0.15 50 84.5 LuCl₃ 0 12.5 2 0.05 30 19.5(CeLa)Cl₃ −0.5 27.5 2.16 0.15 80 42.5% Reduction from Control

Settlable Filtered solids Turbidity OP TP COD BOD RECl₃ (ml/L) (FAU)(mg/L) (mg/L) (mg/L) (mg/L) YCl₃ 0% 9% 96% 1% 10% 29% LaCl₃ −30% 28%100% 10% 19% 24% CeCl₃ −5% 15% 97% 12% 25% 20% PrCl₃ −43% 24% 97% 15%17% 34% NdCl₃ −43% 23% 97% 12% 21% 12% SmCl₃ −14% 11% 96% 9% 16% 30%EuCl₃ −43% 17% 96% 12% 17% 40% GdCl₃ −24% 18% 96% 23% 21% 33% TbCl₃ −24%12% 94% 4% 12% 35% DyCl3 −14% 9% 91% 7% 10% 24% HoCl₃ 0% 5% 88% 1% 8%28% ErCl₃ −20% 8% 94% 10% 8% 18% TmCl₃ 0% 1% 95% 4% 10% 32% YbCl₃ 0% 9%93% 4% 10% 32% LuCl₃ 0% 7% 91% 1% 6% 7% (CeLa)Cl₃ −10% 16% 98% 4% 15%16%

Example 1C: Single Dose Multiple RE (0.241 Mmol/L RE Dose)

Mixtures of RECl₃ solutions were made with the RE elements and at theconcentrations outlined in the table below. Each solution was made withequal molar amounts of 8 rare earths, thus each RE in the solution was12.5% of the total RE content. These mixtures were chosen based on a 15parameter Design of Experiment (DOE) where each parameter is thepresence of an individual RE. A 16 experiment matrix was generated where1 experiment was no addition of RE and the other 15 experiments had 8 ofthe 15 RE elements present in equal molar concentrations. The 8 RE foreach experiment were determined by the DOE matrix. The matrix isprovided below.

Exp. Y La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu 1 1 0 0 0 1 0 0 1 1 0 10 1 1 1 2 1 1 0 0 0 1 0 0 1 1 0 1 0 1 1 3 1 1 1 0 0 0 1 0 0 1 1 0 1 0 14 1 1 1 1 0 0 0 1 0 0 1 1 0 1 0 5 0 1 1 1 1 0 0 0 1 0 0 1 1 0 1 6 1 0 11 1 1 0 0 0 1 0 0 1 1 0 7 0 1 0 1 1 1 1 0 0 0 1 0 0 1 1 8 1 0 1 0 1 1 11 0 0 0 1 0 0 1 9 1 1 0 1 0 1 1 1 1 0 0 0 1 0 0 10 0 1 1 0 1 0 1 1 1 1 00 0 1 0 11 0 0 1 1 0 1 0 1 1 1 1 0 0 0 1 12 1 0 0 1 1 0 1 0 1 1 1 1 0 00 13 0 1 0 0 1 1 0 1 0 1 1 1 1 0 0 14 0 0 1 0 0 1 1 0 1 0 1 1 1 1 0 15 00 0 1 0 0 1 1 0 1 0 1 1 1 1 16 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

4 gal of simulated wastewater was made as outlined above and allowed tostir for at least 15 min. 10 Imhoff cones were set up and 8 were chargedwith the appropriate amount of a RECl₃ solution such that the finalconcentration would be 0.241 mmol/L RE. Two cones were left as controlsamples. The order of the 15 RE used and the placement of the 2 controlswas randomized. The 10 Imhoff cones were then loaded with simulatedwastewater from the discharge valve. Each 1 L sample was allowed tosettle according to the standard Settable Solids measurement procedure.After 1 hr the volume of settable solids was recorded and a filtered andunfiltered sample of the supernatant was collected. Filtered sampleswere filtered through a 0.45 micron syringe filter and analyzed forortho-phosphorus. Unfiltered samples were analyzed for turbidity, totalphosphorus, chemical oxygen demand (COD), and biochemical oxygen demand(BOD). This process was repeated with the remaining RE solutions. The 2controls in each run were averaged and compared to the results withineach run.

RE concen- RE tration concen- Volume in treated RE tration added waterRare Earth Chloride Mix Distribution (mol/L) (ml) (mmol/L)CeSmEuTbHoErTmYb 12.5% Each 1.98 0.122 0.241 YCeNdSmEuGdErLu 12.5% Each1.91 0.126 0.241 LaNdSmGdDyHoErTm 12.5% Each 1.89 0.127 0.241YLaSmTbDyErYbLu 12.5% Each 1.97 0.122 0.241 YCePrNdSmDyTmYb 12.5% Each2.08 0.116 0.241 YLaPrSmEuGdTbTm 12.5% Each 1.92 0.125 0.241YLaCeEuDyHoTmLu 12.5% Each 2.17 0.111 0.241 YPrNdEuTbDyHoEr 12.5% Each2.01 0.120 0.241 LaCePrNdTbErTmLu 12.5% Each 2.06 0.117 0.241YLaCePrGdHoErYb 12.5% Each 2.03 0.119 0.241 LaPrNdSmEuHoYbLu 12.5% Each1.84 0.131 0.241 LaCeNdEuGdTbDyYb 12.5% Each 1.90 0.127 0.241PrEuGdDyErTmYbLu 12.5% Each 1.93 0.125 0.241 CePrSmGdTbDyHoLu 12.5% Each1.86 0.130 0.241 None — — — — YNdGdTbHoTmYbLu 12.5% Each 2.07 0.1170.241Run 1

Settlable Filtered solids Turbidity OP TP COD BOD RECl₃ (ml/L) (FAU)(mg/L) (mg/L) (mg/L) (mg/L) YLaCeEuDyHoTmLu 7 155 0.24 3.2 510 198CeSmEuTbHoErTmYb 7.5 153 0.26 3.2 480 215 YLaPrSmEuGdTbTm 6.5 152 0.243.1 470 248 Control 4.5 171 2.7 3.4 520 269 LaNdSmGdDyHoErTm 7 156 0.263.2 490 192 YCeNdSmEuGdErLu 7 136 0.16 3.1 450 159 YCePrNdSmDyTmYb 6.5147 0.18 3.2 450 183 YPrNdEuTbDyHoEr 7 153 0.18 3.1 490 156YLaSmTbDyErYbLu 6 160 0.22 3.3 480 178 Control 4.5 171 2.8 3.3 530 250Run 2

Settlable Filtered solids Turbidity OP TP COD BOD RECl₃ (ml/L) (FAU)(mg/L) (mg/L) (mg/L) (mg/L) PrEuGdDyErTmYbLu 6.5 150 0.16 3.3 480 177LaCePrNdTbErTmLu 5.5 154 0.16 3.3 500 191 YNdGdTbHoTmYbLu 6 158 0.26 3.2500 206 LaCeNdEuGdTbDyYb 6.5 145 0.1 3.1 450 194 Control 4.5 164 2.2 3.4510 261 CePrSmGdTbDyHoLu 6 139 0.12 3.2 430 158 Control 4.75 166 2.3 3.4530 268Run 3%

Settlable Filtered solids Turbidity OP TP COD BOD RECl₃ (ml/L) (FAU)(mg/L) (mg/L) (mg/L) (mg/L) Control 5 161 2.5 4.2 530 264 None 5 168 2.53.4 500 351 YLaCePrGdHoErYb 6.5 125 0.1 3 430 180 LaPrNdSmEuHoYbLu 6 1300.06 3.2 420 134 Control 5 178 2.6 3.4 500 316% Reduction from Control

Settlable Filtered solids Turbidity OP TP COD BOD RECl₃ (ml/L) (FAU)(mg/L) (mg/L) (mg/L) (mg/L) CeSmEuTbHoErTmYb −67% 11% 91% 4% 9% 17%YCeNdSmEuGdErLu −56% 20% 94% 7% 14%  39% LaNdSmGdDyHoErTm −56%  9% 91%4% 7% 26% YLaSmTbDyErYbLu −33%  6% 92% 1% 9% 31% YCePrNdSmDyTmYb −44%14% 93% 4% 14%  29% YLaPrSmEuGdTbTm −44% 11% 91% 7% 10%   4%YLaCeEuDyHoTmLu −56%  9% 91% 4% 3% 24% YPrNdEuTbDyHoEr −56% 11% 93% 7%7% 40% LaCePrNdTbErTmLu −19%  7% 93% 3% 4% 28% YLaCePrGdHoErYb −30% 26%96% 21%  17%  38% LaPrNdSmEuHoYbLu −20% 23% 98% 16%  18%  54%LaCeNdEuGdTbDyYb −41% 12% 96% 9% 13%  27% PrEuGdDyErTmYbLu −41%  9% 93%4% 8% 33% CePrSmGdTbDyHoLu −30% 16% 95% 6% 17%  40% None  0%  1%  2%11%  3% −21%  YNdGdTbHoTmYbLu −30%  4% 88% 6% 4% 22%

An analysis of this DOE data confirms the results seen in the individualrare earth dosing experiments in that each rare earth is capable ofremoving turbidity, OP, TP, COD, and BOD and that the lighter REs mayperform better than the heavy REs.

Example 1D: Single Dose Single RE (0.3 Mmol/L RE Dose)

A RECl₃ solution was made at the concentrations outlined in the tablebelow. 3 gal of simulated wastewater made as outlined above and allowedto stir for at least 15 min. A 3×1 L samples were collected in Imhoffcones from the discharge valve as a control. Rare earth chloride wasthen dosed into the simulated wastewater solution such that the final REconcentration in the mixture was 0.3 mmol/L. The mixture was allowed tostir for 30 min before 3×1 L samples were collected as before. Each 1 Lsample was allowed to settle according to the standard Settable Solidsmeasurement procedure. After 1 hr the volume of settable solids wasrecorded. The average reading from the 3 Imhoff cones is reported. Equalvolumes from each set of 3 cones was collected and mixed for both thefiltered and unfiltered samples of the supernatant. Filtered sampleswere filtered through a 0.45 micron syringe filter and analyzed forortho-phosphorus. Unfiltered samples were analyzed for turbidity, totalphosphorus, total organic carbon, chemical oxygen demand, andbiochemical oxygen demand.

RE RE concentration in Rare Earth RE concentration Volume treated waterChloride Distribution (mol/L) added (ml) (mmol/L) YCl₃ ≥99.9% Y 3.130.077 0.3 LaCl₃ ≥99.9% La 1.95 0.124 0.3 CeCl₃ ≥99.9% Ce 2.43 0.099 0.3PrCl₃ ≥99.9% Pr 1.85 0.130 0.3 NdCl₃ ≥99.9% Nd 1.89 0.127 0.3 SmCl₃≥99.9% Sm 1.47 0.164 0.3 EuCl₃ ≥99.9% Eu 1.73 0.140 0.3 GdCl₃ ≥99.9% Gd1.53 0.157 0.3 TbCl₃ ≥99.9% Tb 1.94 0.124 0.3 DyCl₃ ≥99.9% Dy 1.99 0.1210.3 HoCl₃ ≥99.9% Ho 2.04 0.118 0.3 ErCl₃ ≥99.9% Er 1.97 0.122 0.3 TmCl₃≥99.9% Tm 2.84 0.085 0.3 YbCl₃ ≥99.9% Yb 1.99 0.121 0.3 LuCl₃ ≥99.9% Lu1.97 0.122 0.3Data

Settlable Filtered solids Turbidity OP TP TOC COD BOD RECl₃ (ml/L) (FAU)(mg/L) (mg/L) (mg/L) (mg/L) (mg/L) Control 5.2 196 1.9 3.9 180 470 199YCl₃ 7.0 147 0.2 3.4 146 420 106 Control 4.8 164 3 3.6 182 510 263 LaCl₃7 94 0.16 3 146 380 175 Control 4.8 160 2.7 3.6 186 490 324 CeCl₃ 6.5 850.14 3.1 144 360 150 Control 4.5 158 2.7 3.9 178 530 309 PrCl₃ 6.2 1080.18 3.3 148 420 149 Control 4.8 161 2.5 3.3 186 480 284 NdCl₃ 6.7 950.1 2.8 148 400 155 Control 4.7 168 2.9 4 178 510 339 SmCl₃ 5.7 121 0.223.4 158 470 161 Control 4.5 192 2.0 3.8 162 480 235 EuCl₃ 6.8 142 0.143.2 130 370 146 Control 4.7 162 2.9 3.7 178 520 334 GdCl₃ 5.8 117 0.243.3 154 400 150 Control 4.7 187 1.9 3.8 152 470 218 TbCl₃ 6.7 142 0.163.2 128 380 133 Control 4.8 153 2.9 3.6 170 530 344 DyCl₃ 5.5 121 0.323.2 156 440 153 Control 4.5 159 3 4 180 530 287 HoCl₃ 5.5 137 0.5 3.2176 460 206 Control 5.0 178 3 3.8 190 590 283 ErCl₃ 5.8 148 0.52 3.7 182500 196 Control 4.7 159 2.6 3.9 182 460 264 TmCl₃ 5.5 122 0.34 3.5 166420 174 Control 4.8 168 2.6 3.5 180 550 258 YbCl₃ 5.5 137 0.44 3.3 174450 143 Control 4.8 165 3 3.5 178 550 271 LuCl₃ 5.5 140 0.58 3.3 174 480134Difference from Control

Settlable Filtered solids Turbidity OP TP TOC COD BOD RECl₃ (ml/L) (FAU)(mg/L) (mg/L) (mg/L) (mg/L) (mg/L) YCl₃ −1.8 49 1.7 0.5 34 50 93 LaCl₃−2.2 70 2.8 0.6 36 130 88 CeCl₃ −1.7 75 2.6 0.5 42 130 174 PrCl₃ −1.7 502.5 0.6 30 110 160 NdCl₃ −1.8 66 2.4 0.5 38 80 129 SmCl₃ −1.0 47 2.7 0.620 40 178 EuCl₃ −2.3 50 1.9 0.6 32 110 89 GdCl₃ −1.2 45 2.7 0.4 24 120184 TbCl₃ −2.0 45 1.7 0.6 24 90 85 DyCl₃ −0.7 32 2.6 0.4 14 90 191 HoCl₃−1.0 22 2.5 0.8 4 70 81 ErCl₃ −0.8 30 2.5 0.1 8 90 87 TmCl₃ −0.8 37 2.30.4 16 40 90 YbCl₃ −0.7 31 2.2 0.2 6 100 115 LuCl₃ −0.7 25 2.4 0.2 4 70137% Reduction from Control

Settlable Filtered solids Turbidity OP TP TOC COD BOD RECl₃ (ml/L) (FAU)(mg/L) (mg/L) (mg/L) (mg/L) (mg/L) YCl₃ −35% 25% 89% 13% 19% 11% 47%LaCl₃ −45% 43% 95% 17% 20% 25% 33% CeCl₃ −34% 47% 95% 14% 23% 27% 54%PrCl₃ −37% 32% 93% 15% 17% 21% 52% NdCl₃ −38% 41% 96% 15% 20% 17% 45%SmCl₃ −21% 28% 92% 15% 11%  8% 53% EuCl₃ −52% 26% 93% 16% 20% 23% 38%GdCl₃ −25% 28% 92% 11% 13% 23% 55% TbCl₃ −43% 24% 92% 16% 16% 19% 39%DyCl₃ −14% 21% 89% 11%  8% 17% 56% HoCl₃ −22% 14% 83% 20%  2% 13% 28%ErCl₃ −17% 17% 83%  3%  4% 15% 31% TmCl₃ −18% 23% 87% 10%  9%  9% 34%YbCl₃ −14% 18% 83%  6%  3% 18% 45% LuCl₃ −14% 15% 81%  6%  2% 13% 51%

Example 1E: Multiple Doses (0.116 Mmol/L RE Dose)

A RECl₃ solution was made at the concentrations outlined in the tablebelow. 3 gal of simulated wastewater made as outlined above and allowedto stir for at least 15 min. A 3×1 L samples were collected in Imhoffcones from the discharge valve as a control. Rare earth chloride wasthen dosed into the simulated wastewater solution in 6 increments, 1dose every 5 min, such that the final RE concentration in the mixturewas 0.116 mmol/L. The mixture was allowed to stir for at least 5 minbefore 3×1 L samples were collected as before. For one experiment, CeCl₃solution was dosed in a single increment to reach the 0.116 mmol/Lconcentration and allowed to stir for 30 min. The pH of the mixture wasrecorded when each sample was taken. Each 1 L sample was allowed tosettle according to the standard Settable Solids measurement procedure.After 1 hr the volume of settable solids was recorded. The averagereading from the 3 Imhoff cones is reported. Equal volumes from each setof 3 cones was collected and mixed for both the filtered and unfilteredsamples of the supernatant. Filtered samples were filtered through a0.45 micron syringe filter and analyzed for ortho-phosphorus. Unfilteredsamples were analyzed for turbidity, total phosphorus, total organiccarbon, chemical oxygen demand, biochemical oxygen demand, and totalsuspended solids.

RE Rare Earth concentration Chloride RE Distribution (mol/L) CeCl₃≥99.9% Ce 2.43 (CeLa)Cl₃ 66.6% Ce, 33.3% La 2.11 (CeLaY)Cl₃ 33.3% Ce,16.6% La, 50% Y 2.61 (CeLaSm)Cl₃ 33.3% Ce, 16.6% La, 50% Sm 1.77(CeLaSmY)Cl₃ 33.3% Ce, 16.6% La, 25% Sm, 25% Y 2.11Data

Settlable Filtered solids Turbidity OP TP TOC COD BOD TSS RECl₃ (ml/L)(FAU) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) Control 5.5 195 2.2 4166 490 256 161 Single dose 8.7 77 0.3 2.4 144 340 165 123 CeCl₃ Control5.0 180 2.2 3.6 160 470 217 136 Multi-dose 9.0 37 0.2 1.6 94 290 102 53CeCl₃ Control 5.0 183 2.1 3.7 166 470 229 121 Multi-dose 8.5 43 0.24 292 300 152 48 (CeLa)Cl₃ Control 4.8 179 2.6 4.1 148 520 246 145Multi-dose 7.2 100 0.38 3 118 380 195 92 (CeLaY)Cl₃ Control 5.0 191 2.43.6 162 480 240 127 Multi-dose 7.7 72 0.2 2.5 106 330 171 50 (CeLaSm)Cl₃Control 4.8 177 2.4 3.7 148 500 260 130 Multi-dose 7.7 80 0.32 3.4 110360 178 126 (CeLaSmY)Cl₃Difference from Control

Settlable Filtered solids Turbidity OP TP TOC COD BOD TSS RECl₃ (ml/L)(FAU) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) Single dose −3.2 118 1.91.6 22 150 91 38 CeCl₃ Multi-dose −4.0 143 2.0 2.0 66 180 115 83 CeCl₃Multi-dose −3.5 140 1.9 1.7 74 170 77 73 (CeLa)Cl₃ Multi-dose −2.7 1192.2 1.1 56 150 69 77 (CeLaY)Cl₃ Multi-dose −2.3 79 2.2 1.1 30 140 51 53(CeLaSm)Cl₃ Multi-dose −2.8 97 2.1 0.3 38 140 82 4 (CeLaSmY)Cl₃% Reduction

Settlable Filtered solids Turbidity OP TP TOC COD BOD TSS RECl₃ (ml/L)(FAU) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) Single dose −58% 61% 86%40% 13% 31% 36% 24% CeCl₃ Multi-dose −80% 79% 91% 56% 41% 38% 53% 61%CeCl₃ Multi-dose −70% 77% 89% 46% 45% 36% 34% 60% (CeLa)Cl₃ Multi-dose−53% 62% 92% 31% 35% 31% 29% 61% (CeLaY)Cl₃ Multi-dose −48% 44% 85% 27%20% 27% 21% 37% (CeLaSm)Cl₃ Multi-dose −59% 55% 87%  8% 26% 28% 32%  3%(CeLaSmY)Cl₃Analytical Testing Methods Used

Settleable Solids: 1 liter of influent was place in an Imhoff cone andallowed to settle for 45 min. The supernatant was gently stirred toloosen solids from the wall. Settling continued for an addition 15 min.The volume of solids was then recorded.

Turbidity: Hach Method 8237

Total Suspended Solids (TSS): SM 2540 D-97

Total Phosphorus (TP): Hach Method 8180

Filtered Orthophosphate (FOP): 10 ml samples were filtered through a0.45 micron syringe filter.

Resulting solution was analyzed by Hach Method 8048

Chemical Oxygen Demand (COD): Hach Method 8000

Biochemical Oxygen Demand (BOD): SM 5210 B-01

Total Organic Carbon (TOC): Hach Method 10173

Conclusion:

A simulated wastewater was made as outlined above and dosed withdifferent amounts and compositions of RECl₃ solutions. Addition of REresulted in an overall reduction in Turbidity, OP, TP, TOC, COD, BOD,and TSS. Small doses of RE resulted in a decrease in the settlablesolids, while larger doses resulted in an increase in settlable solids.This works for all RE but appears to provide better results for thelighter REs. Also, it appears that dosing the RE incrementally yields agreater difference between the control and the final sample.

These experiments indicate that how fast the RE is added may change theresults. Thus, in an embodiment in which a plant is runningcontinuously, multiple dose points may be advantageous. In a plant thatis running batch, a slower dose rate may be more favorable.

Example 2: Experimental Data Generated from Simulated Wastewater:Comparison of RE, Ferric, and Alum Solution

Synthesis of Rare Earth Chloride Solution:

Individual RECl₃ solutions and mixtures of RECl₃ solutions were preparedas described above in Example 1.

Simulated Wastewater:

Simulated wastewater was created as described above in Example 1.

Results and Experimental:

Single Dose Single RE, 0.243 Mmol/L RE Dose

A RECl₃ solution was made at the concentrations outlined in the tablebelow via the method outlined above. 4 gal of simulated wastewater wasmade and allowed to stir for at least 15 min. 10 Imhoff cones were setup and some were charged with 0.100 ml of RECl₃, Ferric, or Alumsolution. Two cones were left as control samples. The order of theplacement of the 2 controls was randomized. The Imhoff cones were thenloaded with simulated wastewater from the discharge valve. Each 1 Lsample was allowed to settle according to the standard Settable Solidsmeasurement procedure. After 1 hr the volume of settable solids wasrecorded and a filtered and unfiltered sample of the supernatant wascollected. Filtered samples were filtered through a 0.45 micron syringefilter and analyzed for ortho-phosphorus. Unfiltered samples wereanalyzed for turbidity, total phosphorus, and chemical oxygen demand(COD). This process was repeated. The 2 controls in each run wereaveraged and compared to the results within each run.

RE Volume RE concentration in Rare Earth RE concentration added treatedwater Chloride Distribution (mol/L) (ml) (mmol/L) CeCl₃ ≥99.9% Ce 2.430.100 0.243 (CeLa)Cl₃ 66.67% Ce, 2.25 0.100 0.225 33.33% LaFerric solution description: 30% wt/wt FeCl₃ water solution, pH<1commercially available sampleAlum solution description: 30% wt/wt Al₂(SO₄)₃ water solutioncommercially available sampleRun 1

Settlable solids Turbidity Filtered OP TP COD RECl₃ (ml/L) (FAU) (mg/L)(mg/L) (mg/L) Control 5 176 1.55 3.3 500 FeCl₃ 5.5 185 0.25 3.2 470 Alum5.5 171 1.15 3.2 470 (CeLa)Cl₃ 6 176 ≤0.05 3.2 440 CeCl₃ 7 159 ≤0.05 3330 Control 5 174 1.65 3.2 430Run 1 Difference from Control (Average of Controls−Dose Value)

Settlable solids Turbidity Filtered OP TP COD RECl₃ (ml/L) (FAU) (mg/L)(mg/L) (mg/L) CeCl₃ −2 16 1.6 0.25 135 (CeLa)Cl₃ −1 −1 1.6 0.05 25 FeCl₃−0.5 −10 1.35 0.05 −5 Alum −0.5 4 0.45 0.05 −5Run 1% Reduction from Control

Settlable solids Turbidity Filtered OP TP COD RECl₃ (ml/L) (FAU) (mg/L)(mg/L) (mg/L) CeCl₃ −40% 9% ≥97% 8% 29% (CeLa)Cl₃ −20% −1% ≥97% 2% 5%FeCl₃ −10% −6% 84% 2% −1% Alum −10% 2% 28% 2% −1%Run 2

Settlable solids Turbidity Filtered OP TP COD RECl₃ (ml/L) (FAU) (mg/L)(mg/L) (mg/L) Control 4.5 172 1.65 3.3 480 CeCl₃ 7.5 125 ≤0.05 2.7 330FeCl₃ 6 181 0.25 3.3 390 Alum 5.5 165 1 3.4 460 Control 4.5 171 1.7 3.3460Run 2 Difference from Control (Average of Controls−Dose Value)

Settlable solids Turbidity Filtered OP TP COD RECl₃ (ml/L) (FAU) (mg/L)(mg/L) (mg/L) CeCl₃ −3 46.5 1.675 0.6 140 FeCl₃ −1.5 −9.5 1.425 0 80Alum −1 6.5 0.675 −0.1 10Run 2% Reduction from Control

Settlable solids Turbidity Filtered OP TP COD RECl₃ (ml/L) (FAU) (mg/L)(mg/L) (mg/L) CeCl₃ −67% 27% ≥97% 18% 31% FeCl₃ −33% −5% 85% 0% 19% Alum−22% 4% 39% −3% 4%

Analytical Testing methods were as described in Example 1.

Conclusion:

A simulated wastewater was made and dosed with RECl₃, Ferric, and Alumsolutions. Addition of RE resulted in an overall greater reduction inTurbidity, OP, TP, and COD when compared to Ferric or Alum. Doses of REalso resulted in a greater increase in settlable solids when compared toFerric or Alum.

Example 3: Primary Influent Testing

General Product Synthesis:

RE chloride crystals (RECl₃·xH₂O where x can range from 0-10 but istypically around 6-8) are dissolved in water. The amount of crystals vsthe amount of water will determine the final concentration. The pH isadjusted to 3-4. The product is then filtered through a 10 micron filterand a sample is tested for multiple impurities, with Fe, Pb, and U beingthe ones of primary importance.

Mixed RE Solution Used in Primary Influent Testing:

A (CeLa)Cl₃ solution was produced using the above general procedureusing a RECl₃ that was

RE %

Weighted average from analysis of Highest Lowest crystals in specificAverage of all Observed Observed lot used historical lots Value ValueCe/RE 63.43% 63.261% 70.100% 59.840% La/RE 36.56% 34.729% 40.160%29.900% Pr/RE 0.008% 0.005% 0.008% 0.001% Nd/RE 0.005% 0.004% 0.005%0.001% Sm/RE <0.005%  <0.001% Y/RE <0.005%  <0.001% Other RE elementswere not measured.pH=3; Density=1.562 g/ml; RECl₃ conc: 41.1%, 642 g/L; REO conc: 437 g/LImpurities (estimated from weighted average of analysis of crystals usedto make specific lot): Fe 43.5 mg/L; Pb 3.11 mg/L; U 0.62 mg/L (withother elements not measured)Single RE Solution Used in Testing:

A CeCl₃ solution was produced using the above general procedure using aRECl₃ that was RE %: Ce/RE 99.980%; La/RE 0.010%; Pr/RE 0.003%; Nd/RE0.003%; Sm/RE 0.001%; Y/RE<0.001% (with other RE elements were notmeasured). pH=3.3; Density=1.57 g/ml; RECl₃ conc: 41.3%, 648 g/L; REOconc: 453 g/L.

Ferric Description:

Density 1.45 g/ml; Concentration 40% (wt/wt) FeCl₃

Alum Description:

Density 1.33 g/ml; Concentration 50% (wt/wt) Al₂(SO₄)₃

Dosing was performed in the primary clarifier and significantimprovements in the plant operations were noticed. It appears that theefficiency of subsequent plant operations (like a trickling filter,anaerobic digester, filter press, etc.) can be controlled by controllingthe dose in the primary. The following experiments were designed toinvestigate the function of RE in the primary clarifier.

The influent from a 0.6 MGD wastewater treatment plant in Pennsylvaniawas collected after the grit screen and prior to the primary clarifierand tested with varying doses of the Mixed RE solution ((CeLa)Cl₃). Onetest was done using a low dose of RE and compared to equal molar dosesof Fe and Al as ferric and alum.

The plant flow was as illustrated in FIG. 3A with the RE dosed prior tothe primary clarifier.

Results:

Primary Clarifier Influent

Primary Clarifier influent was dosed with varying amounts of RE. Thisexperiment was performed 2 times, once using small doses of RE (Test 1)and once using a larger doses of RE (Test 2). The settlable solids,turbidity, filtered orthophosphate (OP), total phosphorus (TP), chemicaloxygen demand (COD), Biochemical Oxygen Demand (BOD), and total organiccarbon (TOC) were measured. Each was plotted vs the dosed RE amount inmmol/L treated water. The % change of each[%=(Control−dosed)/control×100] was calculated and plotted. Test 1Settlable Solids, filtered OP and unfiltered TP is shown in FIG. 3B.Test 1 Settlable Solids, Turbidity, COD, BOD, and TOC is shown in FIG.3C. Test 1% Reduction All Data is shown in FIG. 3D. Test 2 SettlableSolids, filtered OP and unfiltered TP is shown in FIG. 3E. Test 2Settlable Solids, Turbidity, COD, BOD, and TOC is shown in FIG. 3F. Test2% Reduction All Data is shown in FIG. 3G.

Coagulant Comparison Testing

Raw influent from the wastewater treatment plant in Pennsylvania wasdosed with equal molar amounts of RE, Fe, and Al. The dose amount was0.015 mmol/L of treated solution. The total organic carbon (TOC),chemical oxygen demand (COD), filtered orthophosphate (FOP), unfilteredorthophosphate (UOP), total phosphorus (TP), turbidity, and BiochemicalOxygen Demand (BOD) were measured. The % change of each[%=(Control−dosed)/control×100] was calculated and plotted.

Measured Data

Control RE Ferric Alum Settlable Solids (ml/L) 24 20 22 24 Turbidity(FAU) 77 77 75 73 Unfiltered TP (mg/L) 4.9 4.4 3.8 4.6 Filtered OP(mg/L) 1.7 0.9 1.7 1.2 COD (mg/L) 170 180 170 210 BOD (mg/L) 57.3 67.155.9 55.7 TOC (mg/L) 93 86 96 92Difference from Control

Control RE Ferric Alum Settlable Solids (ml/L) — 4 2 0 Turbidity (FAU) —0 2 4 Unfiltered TP (mg/L) — 0.5 1.1 0.3 Filtered OP (mg/L) — 0.8 0 0.5COD (mg/L) — −10 0 −40 BOD (mg/L) — −9.8 1.4 1.6 TOC (mg/L) — 7 −3 1% Reduction from Control

Control RE Ferric Alum Settlable Solids — 17% 8% 0% Turbidity — 0% 3% 5%Unfiltered TP — 19% 8% 23% Filtered OP — 47% 0% 29% COD — −6% 0% −24%BOD — −17% 2% 3% TOC — 8% −3% 1%Experimental:

Raw Influent Test 1:

In a wastewater treatment plant, approximately 13 L of raw sewageinfluent was collected after the grit filter but prior to the primaryclarifier. The sample was stirred and separated into 5 portions, a 1 Lcontrol sample, three 3 L samples, and one 2.7 L sample. The 1 L controlsample was loaded into an Imhoff cone and the standard settleable solidsmeasurement procedure was followed. Each of the remaining 4 samples werethen dosed with increasing amounts of rare earth (RE) as a RE chloridesolution to make the RE concentration 0.008, 0.013, 0.017, and 0.025mmol/L. The samples were allowed to stir for 10 min and then 1 L of eachwas loaded into an Imhoff cone and the standard settleable solidsmeasurement procedure was followed. After settling the volume of thesettleable solids was recorded. A sample of the supernatant wascollected and tested for Turbidity, TP, filtered OP, COD, BOD, and TOC.

Raw Influent Test 2:

In a wastewater treatment plant, approximately 13 L of raw sewageinfluent was collected after the grit filter but prior to the primaryclarifier. The sample was stirred and separated into 5 portions, a 1 Lcontrol sample, and four 3 L sample. The 1 L control sample was loadedinto an Imhoff cone and the standard settleable solids measurementprocedure was followed. Each of the remaining 4 samples were then dosedwith increasing amounts of rare earth (RE) as a RE chloride solution tomake the RE concentration 0.038, 0.063, 0.089, and 0.114 mmol/L. Thesamples were allowed to stir for 10 min and then 1 L of each was loadedinto an Imhoff cone and the standard settleable solids measurementprocedure was followed. After settling the volume of the settleablesolids was recorded. A sample of the supernatant was collected andtested for Turbidity, TP, filtered OP, COD, BOD, and TOC.

Comparison to Other Coagulants:

In a wastewater treatment plant, approximately 13 L of raw sewageinfluent was collected after the grit filter but prior to the primaryclarifier. The sample was stirred and separated into 4 portions, a 1 Lcontrol sample and three 3 L samples. The 1 L control sample was loadedinto an Imhoff cone and the standard settleable solids measurementprocedure was followed. The remaining 3 samples were then dosed withrare earth (RE) as a RE chloride solution, Ferric chloride, and Aluminumsulfate (Alum) to make the metal (RE, Fe, or Al) concentration 0.015mmol/L. The samples were allowed to stir for 10 min and then 1 L of eachwas loaded into an Imhoff cone and the standard settleable solidsmeasurement procedure was followed. After settling the volume of thesettleable solids was recorded. A sample of the supernatant wascollected and tested for Turbidity, TP, filtered OP, COD, BOD, and TOC.

Analytical Testing methods were as described in Example 1.

Example 4: Plant Data Generated from a 1.5 MGD Wastewater TreatmentPlant in New York

The plant flow and dose point is as illustrated in the Flow Chart shownin FIG. 4. All BOD, TSS, and TP analyses were performed using EPAmethods as described herein. As shown in FIG. 4, the RE dose point isjust after screening and prior to the small or large primary clarifier,which is prior to the secondary clarifier.

This plant dosed Rare Earths (RE) prior to the primary clarifier for 5months. The plant measures BOD, TSS and TP in the influent and effluent.The table below shows the plant data for 15 months prior to dosing REand the 5 months of dosing RE. The RE dose is the mmol of RE added perliter of water treated.

Avg. Inf. Eff. Inf. Eff. Inf. Eff. RE Flow BOD BOD TSS TSS TP TP doseMonth (MGD) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mmol/L) 1 0.758331 17 279 18 5.85 2.84 2 0.526 435 13 392 17 6.20 4.8 3 0.48 479 15 42513 6.70 4 4 0.499 451 15 450 19 7.80 4 5 0.673 413 17 527 22 6 0.774 42117 362 22 7.80 4.9 7 0.722 425 18 265 21 7.40 4.4 8 0.778 516 17 263 175.20 3.7 9 0.937 469 16 241 15 5.20 3.2 10 1.04 279 18 229 16 4.70 3.211 1.22 385 17 227 20 4.70 3.2 12 1.55 200 14 211 19 9.50 2.7 13 1.06294 14 243 19 14 0.768 349 10 331 13 5.00 3 15 0.939 267 11 226 10 3.752.35 16 0.745 463 15 380 2 8.25 1.90 0.208 17 0.946 341 17 326 1 5.761.10 0.100 18 1.257 400 14 338 1 4.80 0.69 0.064 19 0.530 345 10 378 93.88 0.62 0.115 20 0.495 440 9.6 540 8 6.15 0.44 0.114Averages for the Data Above.

Avg. Inf. Eff. Inf. Eff. Inf. Eff. RE Flow BOD BOD TSS TSS TP TP dose(MGD) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mmol/L) Without 0.848381 15 311 17 6.13 3.56 RE With RE 0.795 398 13 392 4 5.77 0.947 0.12Differences of Averages for the Data Above. (without RE−with RE)

Avg. Inf. Eff. Inf. Eff. Inf. Eff. Flow BOD BOD TSS TSS TP TP (MGD)(mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) 0.053 −17 2 −81 13 0.36 2.613% Reduction of Averages for the Data Above

Avg. Inf. Eff. Inf. Eff. Inf. Eff. Flow BOD BOD TSS TSS TP TP (MGD)(mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) 6.6% −4.5% 13.3% −26% 76.5%5.9% 73.4%

Analytical Testing methods were as described in Example 1.

Conclusion:

Wastewater treated at a 1.5 MGD wastewater treatment plant in New Yorkwas treated with (CeLa)Cl₃ solution dosed prior to the primaryclarifier. Addition of RE resulted in an overall reduction in BOD, TSS,and TP. TSS and TP are reduced the most when RE is dosed. These resultsare even more striking as the average for the time period when RE isdosed has higher BOD, TSS and TP with a lower flow rate; thus, theinfluent during the dosing period is more concentrated than thenon-dosing period.

Example 5: Experimental Data Generated from Wastewater Collected from a32 MGD Wastewater Treatment Plant in Virginia

General Product Synthesis was as described in Example 3 above.

Mixed RE Solution Used in Primary Influent Testing:

A (CeLa)Cl₃ solution was prepared as described in Example 3 above, withthe following differences: pH=3.7; Density=1.57 g/ml; RECl₃ conc: 40.2%,631 g/L; REO conc: 416 g/L, 2.46 mol/L.

Single RE Solution Used in Testing:

A CeCl₃ solution was prepared using the above general procedure asdescribed in Example 3 above, with the following differences: pH=3.8;Density=1.545 g/ml; RECl₃ conc: 40.7%, 629 g/L; REO conc: 439 g/L, 2.55mol/L.

The plant flow is as illustrated in the Flow Chart shown in FIG. 5A.

Results and Experimental Example 5A: Raw Wastewater, Dosing with(CeLa)Cl₃

A (CeLa)Cl₃ solution was made at a concentration of 2.46 mol/L RE andthe Ce:La ratio was approximately 2:1. 4 gal of raw wastewater (directlyfrom the headworks of the plant and prior to the grit screen or anypretreatment) was collected and allowed to stir for at least 15 min. A 1L sample was collected in an Imhoff cone from the discharge valve as acontrol. Rare earth chloride was then dosed into the wastewater inincrements such that the RE concentration in the mixture increased byapproximately 0.013 mmol/L each increment for a total of 9 additions.The actual concentration was calculated based on the dose and the volumeof sample removed after sampling. The mixture was allowed to stir for atleast 5 min before a 1 L sample was collected. This process was repeateduntil a total of 10 samples (1 control and 9 additions) were collected.The pH of the mixture was recorded when each sample was taken. Each 1 Lsample was allowed to settle according to the standard Settable Solidsmeasurement procedure. After 1 hr the volume of settable solids wasrecorded and a filtered and unfiltered sample of the supernatant wascollected. Filtered samples were filtered through a 0.45 micron syringefilter and analyzed for ortho-phosphorus. Unfiltered samples wereanalyzed for turbidity, total phosphorus, chemical oxygen demand,biochemical oxygen demand and total suspended solids.

The settlable solids, Unfiltered TP and Filtered OP of each sample weremeasured and plotted vs. the RE concentration in mmol/L, as shown inFIG. 5B. Unfiltered samples of the supernatant from each dosing weremeasured for turbidity, COD, BOD and TSS and this was plotted vs. the REconcentration in mmol/L, as shown in FIG. 5C. % Reduction is illustratedin FIG. 5D.

Example 5B: Primary Influent Wastewater, Dosing with CeCl₃

A CeCl₃ solution was made at a concentration of 2.55 mol/L RE. 4 gal ofwastewater collected from just before the primary clarifier was allowedto stir for at least 15 min. A 1 L sample was collected in an Imhoffcone from the discharge valve as a control. Rare earth chloride was thendosed into the wastewater in increments such that the RE concentrationin the mixture increased by approximately 0.013 mmol/L each incrementfor a total of 9 additions. The actual concentration was calculatedbased on the dose and the volume of sample removed after sampling. Themixture was allowed to stir for at least 5 min before a 1 L sample wascollected. This process was repeated until a total of 10 samples (1control and 9 additions) were collected. The pH of the mixture wasrecorded when each sample was taken. Each 1 L sample was allowed tosettle according to the standard Settable Solids measurement procedure.After 1 hr the volume of settable solids was recorded and a filtered andunfiltered sample of the supernatant was collected. Filtered sampleswere filtered through a 0.45 micron syringe filter and analyzed forortho-phosphorus. Unfiltered samples were analyzed for turbidity, totalphosphorus, chemical oxygen demand, biochemical oxygen demand and totalsuspended solids.

The settlable solids, Unfiltered TP and Filtered OP of each sample weremeasured and plotted vs. the RE concentration in mmol/L, as shown inFIG. 5E. Unfiltered samples of the supernatant from each dosing weremeasured for turbidity, COD, BOD and TSS and this was plotted vs. the REconcentration in mmol/L, as shown in FIG. 5F. % Reduction is illustratedin FIG. 5G.

Example 5C: Primary Influent Wastewater, Dosing with (CeLa)Cl₃

A (CeLa)Cl₃ solution was made at a concentration of 2.46 mol/L RE andthe Ce:La ratio was approximately 2:1. 4 gal of wastewater collectedfrom just before the primary clarifier was allowed to stir for at least15 min. A 1 L sample was collected in an Imhoff cone from the dischargevalve as a control. Rare earth chloride was then dosed into thewastewater in increments such that the RE concentration in the mixtureincreased by approximately 0.007 mmol/L each increment for a total of 9additions. The actual concentration was calculated based on the dose andthe volume of sample removed after sampling. The mixture was allowed tostir for at least 5 min before a 1 L sample was collected. This processwas repeated until a total of 10 samples (1 control and 9 additions)were collected. The pH of the mixture was recorded when each sample wastaken. Each 1 L sample was allowed to settle according to the standardSettable Solids measurement procedure. After 1 hr the volume of settablesolids was recorded and a filtered and unfiltered sample of thesupernatant was collected. Filtered samples were filtered through a 0.45micron syringe filter and analyzed for ortho-phosphorus. Unfilteredsamples were analyzed for turbidity, total phosphorus, chemical oxygendemand, biochemical oxygen demand and total suspended solids.

The settlable solids, Unfiltered TP and Filtered OP of each sample weremeasured and plotted vs. the RE concentration in mmol/L, are shown inFIG. 5H. Unfiltered samples of the supernatant from each dosing weremeasured for turbidity, COD, BOD and TSS and plotted vs. the REconcentration in mmol/L, as shown in FIG. 5I. % Reduction is illustratedin FIG. 5J.

Example 5D: Primary Influent Wastewater, Dosing with CeCl₃

A CeCl₃ solution was made at a concentration of 2.55 mol/L RE. 4 gal ofwastewater collected from just before the primary clarifier was allowedto stir for at least 15 min. A 1 L sample was collected in an Imhoffcone from the discharge valve as a control. Rare earth chloride was thendosed into the wastewater in increments such that the RE concentrationin the mixture increased by approximately 0.007 mmol/L each incrementfor a total of 9 additions. The actual concentration was calculatedbased on the dose and the volume of sample removed after sampling. Themixture was allowed to stir for at least 5 min before a 1 L sample wascollected. This process was repeated until a total of 10 samples (1control and 9 additions) were collected. The pH of the mixture wasrecorded when each sample was taken. Each 1 L sample was allowed tosettle according to the standard Settable Solids measurement procedure.After 1 hr the volume of settable solids was recorded and a filtered andunfiltered sample of the supernatant was collected. Filtered sampleswere filtered through a 0.45 micron syringe filter and analyzed forortho-phosphorus. Unfiltered samples were analyzed for turbidity, totalphosphorus, chemical oxygen demand, biochemical oxygen demand and totalsuspended solids.

The settlable solids, Unfiltered TP and Filtered OP of each sample weremeasured and plotted vs. the RE concentration in mmol/L, as shown inFIG. 5K. Unfiltered samples of the supernatant from each dosing weremeasured for turbidity, COD, BOD and TSS and plotted vs. the REconcentration in mmol/L, as shown in FIG. 5L. % Reduction is shown as inFIG. 5M.

Example 5E Primary Influent Wastewater Room Temperature and Chilled,Dosing with (CeLa)Cl₃

A (CeLa)Cl₃ solution was made at a concentration of 2.46 mol/L RE andthe Ce:La ratio was approximately 2:1. 8 gal of wastewater collectedfrom just before the primary clarifier. The sample was split into 2×4gal portions. One 4 gal portion was allowed to sit at room temperatureovernight while the other was placed in a refrigerator set to 4° C.overnight. In the morning each was allowed to stir for at least 15 min.The measured temperature of the room temperature sample was 21.3° C.(70.34° F.) while the chilled sample was 12.5° C. (54.68° F.). A 1 Lsample was collected in an Imhoff cone from the discharge valve as acontrol. Rare earth chloride was then dosed into the wastewater inincrements such that the RE concentration in the mixture increased byapproximately 0.012 mmol/L each increment for a total of 4 additions.The actual concentration was calculated based on the dose and the volumeof sample removed after sampling. The mixture was allowed to stir for atleast 5 min before a 1 L sample was collected. This process was repeateduntil a total of 5 samples (1 control and 4 additions) were collected.The pH of the mixture was recorded when each sample was taken. Each 1 Lsample was allowed to settle according to the standard Settable Solidsmeasurement procedure. After 1 hr the volume of settable solids wasrecorded and a filtered and unfiltered sample of the supernatant wascollected. Filtered samples were filtered through a 0.45 micron syringefilter and analyzed for ortho-phosphorus. Unfiltered samples wereanalyzed for turbidity, total phosphorus, chemical oxygen demand,biochemical oxygen demand and total suspended solids. The COD of thefinal dose chilled sample was not measured.

The settlable solids, Unfiltered TP and Filtered OP of each sample weremeasured and plotted vs. the RE concentration in mmol/L, as shown inFIG. 5N. Unfiltered samples of the supernatant from each dosing weremeasured for turbidity, COD, BOD and TSS and plotted vs. the REconcentration in mmol/L, as shown in FIG. 5O and FIG. 5P. % Reduction atRT is as shown in FIG. 5Q and % Reduction Chilled is as shown in FIG.5R.

Analytical Testing methods were as described in Example 1.

Conclusion:

Wastewater samples from a 32 MGD wastewater treatment plant in Virginiawere collected and dosed with CeCl₃ and (CeLa)Cl₃ solutions. Addition ofRE resulted in an overall reduction in Turbidity, OP, TP, COD, BOD, andTSS; as well as an increase in settlable solids. Dosing at chilledsample has similar effects but dosing at lower temperatures does notappear to offer an advantage over dosing at warmer temperatures.

Unless otherwise indicated, all numbers expressing quantities ofingredients, properties such as molecular weight, reaction conditions,and so forth used in the specification and claims are to be understoodas being modified in all instances by the term “about.” Accordingly,unless indicated to the contrary, the numerical parameters set forth inthe following specification and attached claims are approximations thatmay vary depending upon the desired properties sought to be obtained.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the technology are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical value, however, inherently contain certainerrors necessarily resulting from the standard deviation found in theirrespective testing measurements.

It will be clear that the compositions and methods described herein arewell adapted to attain the ends and advantages mentioned as well asthose inherent therein. Those skilled in the art will recognize that themethods and systems within this specification may be implemented in manymanners and as such are not to be limited by the foregoing exemplifiedembodiments and examples. In this regard, any number of the features ofthe different embodiments described herein may be combined into onesingle embodiment and alternate embodiments having fewer than or morethan all of the features herein described are possible.

While various embodiments have been described for purposes of thisdisclosure, various changes and modifications may be made which are wellwithin the scope contemplated by the present disclosure. Numerous otherchanges may be made which will readily suggest themselves to thoseskilled in the art and which are encompassed in the spirit of thedisclosure.

What is claimed is:
 1. A method for treating wastewater, includingremoving phosphorus while maintaining a ratio of C—P, comprising: dosingwastewater as part of a primary treatment or before the primarytreatment with a clarifying agent of chloride salts of Ce and La havingfrom 55.0-75.0% Ce and from 25.0-45.0% La and any balance being chloridesalts of other rare earth elements, in an amount to provide a rare earth(RE):phosphorus (P) molar ratio of approximately 0.1:1 RE:P toapproximately 0.8:1 RE:P and at a rare earth concentration of 0.01 to0.5 mmol/L of wastewater, wherein the dosing provides a ratio of C to Pranging from 150 C:1 P to 25 C:1 P for dosed wastewater and wherein thedosing reduces one or more of orthophosphate (OP), total phosphorous(TP), total organic carbon (TOC), chemical oxygen demand (COD), andbiochemical oxygen demand (BOD); and passing the dosed wastewater to asecondary treatment, wherein the ratio of C to P maintainsmicroorganisms in the secondary treatment.
 2. The method of claim 1,wherein the wastewater is dosed to provide a rare earth concentration of0.03 to 0.30 mmol RE/L wastewater.
 3. The method of claim 1, wherein thebalance of chloride salts of other rare earth elements is less than 2%.4. The method of claim 3, wherein the chloride salts of other rare earthelements are selected from the group consisting of Pr, Nd, Sm, Y, andmixtures thereof.
 5. The method of claim 1, wherein the clarifying agentcontains less than 10 g/L of sodium, iron, lead, uranium, and mixturesthereof.
 6. The method of claim 1, wherein the clarifying agent ofchloride salts of Ce and La has from 60.0-65.0% Ce and 30.0-40.0% La andthe balance being one or more of chloride salts of other rare earthelements.
 7. The method of claim 1, wherein the clarifying agent ofchloride salts of Ce and La has from 59.8-70.1% Ce and from 29.9-40.1%La and the balance being one or more of chloride salts of any other rareearth elements.
 8. The method of claim 1, wherein the clarifying agentof is an aqueous solution of chloride salts of Ce and La.
 9. The methodof claim 1, wherein dosing achieves a ratio of C to P ranging from 100C:1 P to 50 C:1 P for the wastewater.
 10. The method according to claim1, wherein the wastewater is dosed with the clarifying agent upstream ofthe primary treatment, in the primary treatment, or both upstream of andin the primary treatment.
 11. The method of claim 10, wherein thewastewater is dosed with the clarifying agent at multiple dose points.12. The method of claim 10, wherein the wastewater is dosed with theclarifying agent upstream of the primary treatment and prior to a gritscreen or any pretreatment.
 13. The method of claim 10, wherein theprimary treatment is continuous and the wastewater is dosed with theclarifying agent at multiple dose points.
 14. The method of claim 1,wherein the dosing reduces turbidity, orthophosphate (OP), totalphosphorous (TP), total organic carbon (TOC), chemical oxygen demand(COD), biochemical oxygen demand (BOD), and total suspended solids(TSS).
 15. The method of claim 1, wherein the wastewater is dosed in anamount to provide a RE:P molar ratio of approximately 0.1:1 to 0.5:1 andat a rare earth concentration of 0.013 mmol/L to 0.052 mmol/L ofwastewater.
 16. The method of claim 1, wherein the wastewater is dosedin an amount to provide a RE:P molar ratio of approximately 0.4:1 to0.8:1 and at a rare earth concentration of 0.04 mmol/L to 0.09 mmol/L ofwastewater.
 17. The method of claim 1, wherein the wastewater is dosedin an amount to provide a RE:P molar ratio of approximately 0.1:1 to0.4:1 and at a rare earth concentration of 0.04 mmol/L to 0.09 mmol/L ofwastewater.
 18. A method for treating wastewater, including removingphosphorus while maintaining a ratio of C—P, comprising: dosingwastewater as part of a primary treatment or before the primarytreatment with a clarifying agent of chloride salts of a pure rare earthelement of Ce or Sm to provide a rare earth (RE):phosphorus (P) molarratio of approximately 0.1:1 RE:P to approximately 0.8:1 RE:P and at arare earth concentration of 0.01 to 0.5 mmol/L of wastewater, whereinthe dosing provides a ratio of C to P ranging from 150 C:1 P to 25 C:1 Pfor the dosed wastewater and wherein the dosing reduces one or more oforthophosphate (OP), total phosphorous (TP), total organic carbon (TOC),chemical oxygen demand (COD), and biochemical oxygen demand (BOD); andpassing the dosed wastewater to a secondary treatment, wherein the ratioof C to P maintains microorganisms in the secondary treatment.
 19. Themethod of claim 18, wherein the wastewater is dosed in an amount toachieve a ratio of C to P ranging from 100 C:1 P to 50 C:1 P.
 20. Amethod for treating wastewater, including removing phosphorus whilemaintaining a ratio of C—P, comprising: dosing wastewater in multipledoses as part of a primary treatment or before the primary treatmentwith a clarifying agent of chloride salts of Ce and La having from55.0-75.0% Ce and from 25.0-45.0% La and any balance being chloridesalts of other rare earth elements or of chloride salts of Ce, in anamount to provide a rare earth concentration of 0.01 to 0.5 mmol/L ofwastewater, wherein the dosing provides a ratio of C to P ranging from150 C:1 P to 25 C:1 P for dosed wastewater and wherein the dosingreduces one or more of orthophosphate (OP), total phosphorous (TP),total organic carbon (TOC), chemical oxygen demand (COD), biochemicaloxygen demand (BOD), turbidity, and total suspended solids (TSS). 21.The method of claim 20, further comprising the step of passing the dosedwastewater to a secondary treatment, wherein the ratio of C to Pmaintains microorganisms in the secondary treatment.